DISCLAIMER: I do not own Dragon Ball, Dragon Ball Z, or DC Comics.

Black Adam flew at high speed through the air, sparks sizzling around him and crackling across the clouds. He had heard of the Super Saiyan God and planned to destroy this being. If he could destroy the Super Saiyan God he would remove one more obstacle to his objective. He also knew Superman wasn't on Earth at that time, so his plan was timed perfectly, or so he thought.

Goten and Trunks sat on the rug they had laid out on the ground, eating a massive pile of corn and boiled rice. Trunks took a deep breath, tiny bits of corn spraying from his mouth.
"I tell ya Goten… There's nothin' quite like sittin' out here eating whatever we want. And no-one's here to yell at us for our table manners!"
Goten heartily agreed, and started to take another bite of corn when suddenly the two boys felt a massive Ki signature nearby.

"Who is that?" Asked Goten, blinking stupidly.
Trunks cracked the knuckles of his left hand by clenching his fist, and seriously answered, "I don't recognise him. That Ki feels almost as powerful as my dad's!"
Goten closed his eyes. "You sure? Feels weaker than mine."
Trunks nodded. "You're right. But it was high a minute ago. Right now it's barely stronger than my mother's."

Goten and Trunks cried out as the unidentified Ki suddenly spiked, and they quickly took flight, heading towards the unknown enemy.
"That felt even stronger than my big brother!" Cried Goten.
Trunks nodded. He didn't know which Ki level was the right one, but either way this person was not normal. He also knew now that this odd creature was heading towards Goku and Chichi's radish farm, and he hated to think what it might do to Goten's mother if his father wasn't there to protect her.

Black Adam landed heavily on the ground in front of Goku's house, deliberately coming in too hot and creating a shockwave which ripped apart the ground around him.
"Come out and face me, Super Saiyan God! Face the might of Black Adam, an immortal god who shall show you the meaning of the title!"
As he shouted his challenge, a high pitched voice said from behind him, "What a loud mouthed jerk."
Black Adam turned to glare at the speaker, and found himself facing too young boys.
"This is no place for children. Get on your knees and kiss my foot, then you may leave here alive, insolent mortals!"
Goten nodded at this. "You're right, Trunks. He is a jerk."

Hearing the second boy repeat the insult, Black Adam flung a bolt of lightning at the two boys, though the only one it was actually on track to hit was Trunks. The white haired boy sidestepped the bolt, and the two boys rapidly did a strange dance which culminated in the two boys touching fingers and merging together into one boy. This boy was larger than the other two had been, and had the spiky hair of the dark haired boy but had a mixture of dark and white hair. This boy gave a thumbs up sign, then turned it upside down and shook his head, before speaking in a voice that was actually both the boys' voices at once.
"You totally suck, Black Adam! And you can just forget about fighting our dads, because Gotenks is gonna kick your butt so hard you'll be rubbing it for a week!"

With that Gotenks rapidly powered up to Super Saiyan and charged, slamming his fist into the face of the surprised Black Adam, who hadn't expected the boy to have this kind of speed. As Gotenks' punch collided, a shockwave came off his fist and left a crater under Black Adam while also launching him flying into the air. Gotenks rapidly followed him up, punching him repeatedly while yelling out elaborate names for each of his punching moves despite the fact they were just normal punches.

After several of Gotenks' punches landed Black Adam flew away in the opposite direction, outpacing the boy. Black Adam then flung several bolts of lightning at Gotenks, only for Gotenks to dodge each one except the last which he blew apart with a Ki blast, rapidly following up with another Ki blast which connected with Black Adam's face, launching him back. As Black Adam collided sharply with the ground, Gotenks did a cocky dance, shaking his finger back and forth.
"Yeah! Gotenks kicks butt! Maybe you should kiss my foot, you stupid jerk!"

With that Gotenks started striking poses, flexing his muscles and standing in positions he deemed to look cool. As he did that Black Adam recovered and flew at him, slamming into him and dragging him into the air, punching him at high speeds. As the blows landed, Gotenks objected loudly between strikes.
"Will… You… Stop… Hit…ting… Me?!"
Gotenks screamed in aggression as he slammed his fist into Black Adam's oncoming fist, but his knucklebones bruised on impact, and the skin on his hand filled with splits which bled badly, and the surprised Super Saiyan child was sent flying back. As Black Adam charged again, Gotenks slammed into him and was again sent flying back.

The fused warrior landed heavily on his back on the ground, and groaned in pain and annoyance.
"Fine. I still have more!"
Gotenks screamed with renewed vigour, hovering off the ground and powering up to Super Saiyan 3. Black Adam chuckled as he saw Gotenks' now long golden hair, but Gotenks turned and pointed his backside at Black Adam, dropping his pants and mooning the tyrant. Black Adam ground his teeth at this insult, growing angrier as Gotenks started smacking his own backside to taunt Black Adam further.
Gotenks laughed, and jeered, "Yeah! Who's laughing now, you jerk?!"

As Gotenks laughed, Black Adam charged, planting his foot into Gotenks' bared backside and launching him into the air. Gotenks regained his control several hundred metres into the air, where he rapidly pulled his pants back up and rubbed his backside.
"Damn it! Why do these jerks always hit me in the ass?!"

Black Adam watched Gotenks regain control of his movements, and rapidly flew up after Gotenks, swinging his fist at him. Gotenks sensed Black Adam's Ki approaching but wasn't able to react in time to dodge as Black Adam's fist slammed into his chest, launching him higher into the air. Gotenks rubbed his chest in pain, and was still doing so half a second later when Black Adam slammed into him again, punching him in the side and sending him spiralling into the distance.

Gotenks rapidly regained control of his movements, flying away from Black Adam.
"He's strong! Gotta do something!"
Black Adam flew after Gotenks, flying along leisurely knowing he could catch Gotenks. This exact leisurely attitude was exactly what caused him to flinch when Gotenks turned around and exhaled with a deliberately high amount of force, a strange white ghost creature emerging from his mouth. Gotenks followed this by rapidly exhaling five more ghost creatures.
"Yeah! Ghost kamikazes! In your face, Black Adam! One touch and they'll blow your head off!"

Black Adam laughed at this. "You must be joking, weakling. Those creatures are nothing but weak astral projections. You can't harm anything with them. You are weak, boy, and if your fathers don't show up I will kill you instead of them!"
As Black Adam talked, the ghosts had gathered around him, and as he stopped, they instantly charged, all touching him at once and exploding. The sound of Black Adam crying out in a mixture of shock and pain could just barely be heard over the explosions.

Gotenks laughed. "Oh yeah! I just blew him away! Gimme a G, gimme an O, gimme a…"
Black Adam suddenly dashed out of the smoke, slamming his fist into Gotenks again, and rather than launching him away, Black Adam grabbed Gotenks by his hair and continued to punch him as hard as he could. Gotenks blocked some of the strikes, then fired a Ki blast at close range into Black Adam's face, cheering for himself as Black Adam cried out, but Gotenks immediately stopped cheering when Black Adam's hand gripped Gotenks by the face, pulling him to extreme close quarters usually reserved for affectionate couples. Black Adam squeezed Gotenks' forehead as hard as he could, smirking as Gotenks' skull started to bend, resulting in several high pitched screams from Gotenks. Black Adam then gripped Gotenks' neck with his other hand and squeezed his windpipe to choke him. He finished this brutal action by struggling to tear off Gotenks' head.

Gotenks screamed as the bones in his neck started to stretch and fill with cracks, but rapidly started firing blasts into Black Adam's face and chest, using the adrenaline from the pain to fuel his blasts. Finally Gotenks fired one of his largest blasts into Black Adam, forcefully shooting him away. The blast carried Black Adam several hundred miles, carrying him off the land and over the ocean.

Gotenks breathed in deep breaths and rubbed his neck and forehead, feeling the deep bruising there.
"A few more seconds of that and my head might have popped! Gotta blast that bastard!"
Gotenks looked up to see Black Adam had already returned, and was noticeably breathing hard after taking the large blast. Gotenks started to assume a battle stance, but suddenly he separated, reverting back into Goten and Trunks. Black Adam blinked at this, not understanding.

Goten looked at Trunks in horror, while Trunks looked back with the same expression.
"Oh, no!" They cried simultaneously.
Black Adam smirked as he saw the boys despair. He didn't know why they had separated, but he knew that he had won, and since he planned to manually separate the boys from their heads in a few seconds, the reason for their separation wasn't important.

Black Adam started to approach the two terrified boys, but stopped when three new people appeared in front of him, right between him and the boys. One of those people was Superman, and the other two were two men who had spiky black hair similar to the dark haired boy. One of them also bore a striking resemblance to the dark haired boy. Black Adam smirked, and started to charge, when Superman charged forward and punched Black Adam hard enough to leave him sagging backwards.

Black Adam straightened up quickly, but Superman gripped him by the neck and dragged him forward, wrapping his left arm around Black Adam's neck and putting him into a headlock. Black Adam struggled in vain to free himself, and was so focused on how his struggle with Gotenks had left him unable to fight off Superman that he didn't see the now blue haired Vegeta until the Super Saiyan Blue Vegeta had planted his fist into Black Adam's face with such force as to drive Superman back a few metres.

Superman let go of Black Adam, and Black Adam started to attack Vegeta, only for Goku to slam into him by appearing in front of Vegeta using some form of teleportation. Black Adam slumped and dropped to the ground like a limp sack of potatoes, and Vegeta grabbed Goku, spinning him around to face him.
"What the hell do you think you're doing, Kakarot?! I've told you so many times I've lost count! This was my fight, so keep your big hollow head out of it!"
Goku flinched back. "Oh, come on, Vegeta. That guy pounded on Goten too. And it was me he was looking for."
Vegeta gripped Goku by the shirt and glared at him, screaming into his face, "That was MY fight! Not yours! Won't you just once stop stealing the limelight?! Just stay and watch while I kick that bastard's ass!"

While Vegeta was yelling, Black Adam jumped up and started to attack, but Superman caught him and punched him in the ribs hard enough to break several of them. As Black Adam started to attack Superman with a charge of magic electricity, a burst of Heat Vision hit him in the face, launching him back onto the ground. Superman turned back to see Goku and Vegeta had started punching each other. Seeing this, Superman yelled out, "Hey! Focus on the real enemy! Black Adam's the one who came here to kill you!"

Hearing this, Goku and Vegeta stopped fighting, and turned to look at Superman. Goku nodded, and Vegeta ground his teeth, saying, "You're right, and he's also the one who tried to tear off Trunks' head!"
With that, a serious Goku and an enraged Vegeta charged at Black Adam while Superman rapidly cleared out of the way. The two Super Saiyan Blues trapped the exhausted Black Adam between them and punched him repeatedly. The brutal pounding culminated with the two of them trapping Black Adam between two of their most powerful respective Ki blasts. As the blasts exploded, Superman quickly flew into the dust and picked up the shredded and naked Black Adam, flying up above the cloud of dust with the defeated supervillain and holding up his hand to signal Goku and Vegeta to stop. Goku had already ceased and was now stretching his muscles, but Vegeta snarled, wanting to keep blasting Black Adam until there was nothing left of him.

Several seconds passed until Vegeta calmed himself down, reverting to his base form and shrugging.
"You and your stupid pacifistic garbage, Superman. Whatever... Just get that scumbag out of here before I blast his head to pieces. And make sure he has an uncomfortable cell wherever you take him."
As Superman started to fly away, Vegeta called after him, "And just so you and he both know, if he gets out I will vapourise him. That's much more effective than locking him up somewhere so he can get out and kill more people."

Superman nodded sadly and flew away, while Goku stepped up next to Vegeta.
"You know it ain't fair to blame Superman, Vegeta. I'm sure that bad guy won't come near Goten or Trunks again."
Vegeta spat on the ground aggressively. "If Superman wasn't so damn protective of walking pieces of scum I could absolutely guarantee Black Adam would never hurt anyone ever again!"
Goku shrugged, looking up hazily into the air. "Gee… Black Adam's sure lucky Superman called the shots there instead of you, ain't he?"
Vegeta clenched his right fist with enough pressure to crack the knuckle joints.
"Superman can't protect him forever. If Black Adam touches my son or my wife ever again, or either of your sons for that matter, you and I are going to disintegrate him as soon as Superman isn't around to save him."

Goku scratched his head at this, but Vegeta grabbed him by the folds of his gi. "And if you try to say no I'll kick your ass! That bastard is dead as soon as he fucks with my family again!"
Goku cringed back meekly. "Okay, sure! He's gone!"
Watching this exchange between their dads, Goten and Trunks exchanged a glance.
"Gee… I hope for Black Adam's sake he never gets out of prison!" Trunks said cheerfully.

Analysis:

This was in many ways a battle of range. Like a wrestling match where it's reach vs weight. In sheer physical strength, Black Adam was at a vast advantage seeing as his strength is comparable to Shazam's when Shazam is regarded as very similar to Superman in strength, and while he hasn't moved planets like Superman has, he has lifted continents. For the sake of feats we'll ignore the obvious problems with a feat like that, since we all know that realistically the continent would fall apart and Shazam would have just wiped out a civilisation. So in physical strength Black Adam has the edge. By contrast Black Adam's lightning attacks are not powerful enough to match Gotenks' blast attacks though their heat might pose a threat. In short Black Adam has superior physical power but Gotenks has superior energy attacks.

Therefore Gotenks had two things he had to be able to do in order to win. He needed to keep Black Adam at a distance so as to keep blasting him, but he also had to be able to bring Black Adam down before the fusion wears off. By contrast Black Adam has to close the distance since his best bet is to catch Gotenks and crush him with his superior strength. If Black Adam knew about the fusion his best bet would be to keep moving away and waste Gotenks' time until the fusion wore off, but Black Adam wouldn't know about the time limit.

Basically Gotenks had to keep Black Adam at a decent distance but also had to take him down before his fusion time was up, while Black Adam had to get to close quarters, and the longer the fight lasts the worse Gotenks' chances get, and those two things do combine into a bit of a disadvantage, since it makes Gotenks the one who has to win quickly but also the one who has to keep at a distance, which are two conflicting actions. Now, in a fight where range is the decider, the true decider is who can control what range the fighters attack from. In many cases that involves the one who needs to get close enduring the hits to get close, while the other tries to keep away. In the case of two fighters who can fly the one trying to get close can't corner his opponent. In short, the one trying to get close pretty much has to be faster. Black Adam has similar speed to Superman at hundreds or thousands of times light speed, while Gotenks is somewhere between Mach 12,000 and Mach 200,000. That means Black Adam will be able to keep the fight at close range. Then we have the next point, which is that even if the speed difference wasn't factored be it because Black Adam isn't a very tactical fighter or for other reasons, there is also the fact that Gotenks would have to best Black Adam in a very short time. As much as Black Adam isn't anywhere near as tenacious as Superman it's very doubtful Gotenks could best Black Adam in such a short timeframe.