The raw for Prince of Tennis Genius 324 dropped. I can't read Japanese and have no idea what's going on with the funky masks and outfits, but it inspired the following story.
I don't own any of these characters.

The Curse of Planet Spectra

"Here at Centre Neptune, deep beneath the sea, I keep constant watch over the entire galaxy. My name is Seven-Zark-Seven, and today I am watching two very important events. First, G-Force is on Planet Spectra trying to infiltrate Zoltar's forces. Second, Horio Satoshi is in the stands of his school's cheering section at the tennis national competition, watching a match and cheering his little heart out"
Something beeped in the background. The robot who had been speaking ignored it, and continued to talk into his recording device.
"As you all probably know, Horio has two years of tennis experience, and I am just certain that he has a very special future ahead of him. Some people, myself among them, have high hopes that he will be the tennis prodigy that returns Japan to the world stage of tennis champions. Interestingly enough, the last time that this happened it was because of Ryoma Nanjiro, who not only is the father of one of Horio's teammates but also attended the very school where Horio is a student today"
The beeping became more insistent. The robot peered more closely into his monitor, taking care to wipe off some oil that had leaked from his mouth.
"Horio and his two assistants have been placed in a private viewing stand today, showing the great respect that everyone has for him. I just know that his story is going to be a very exciting one"
The beeping stopped.
"Right now he's watching two of his senpais in a doubles match. Let's see how they're doing.

"I can't believe that guy grabbed my ass"
"Well, Mamushi, maybe he just needed to wipe the snot off his hand and your ass was the nearest thing"
"Shut up! That doesn't even make any sense"
Momo grinned. Kaidoh was breathing hard, and sweat dripped on the ground. Momo just kept looking at him.

"Well that's not very exciting, is it? Maybe Horio is interested in something else happening on the court, because I'm sure he has better taste than to care about this sort of vulgarity"
The robot kept staring into his monitor, and a smaller robot entered.
"Wap! Wap"
"Oh, hello One-Rover-One. What's that you say"
"Wap! Wap"
"Oh my! It looks as though G-Force has been trying to contact me on the channel I was supposed to monitor, and I was so entranced while watching Horio that I forgot. Well, they have stopped calling so hopefully they are all fine. Let's have a look"

The Spectra agents finally managed to wrestle Jason's pistol from him, throwing it on the pile with Mark's sonic boomerang, Keyop's bolo, and Princess's yo-yo. He was the last to be handcuffed, and the five members of G-Force were marched off to individual prison cells.
"Mark, why do you think Seven-Zark-Seven didn't answer our calls? He was supposed to give us directions through this complex"
"I don't know, Princess. I just hope that he's still okay down there in Centre Neptune"

"Oh my, I do hope that I can clear this up before Director Anderson hears about it"
The comm unit buzzed.
"This is Director Anderson, calling Seven-Zark-Seven. Come in, Seven-Zark-Seven. I need a status report on G-Force"
"Oh, hello Director Anderson. Is that you? I'm experiencing a lot of static. I'll have to call you back later"
The robot smashed the monitor with a hammer.
"Now then, who can I send into space after G-Force? I'd send Horio, but he's obviously far too important to what's happening to his team for them to be able to spare him"

Ryuzaki-sensei was arguing with the referee, who was clutching a piece of paper. Tezuka stood by with his arms folded, looking on impassively.
"This is ridiculous! I don't care who sent the instructions! I need those boys out on the court"
The referee stayed calm.
"Ryuzaki-sensei, this is a priority directive from President Kane. It says that it's of interplanetary importance that these two go with the pilot. As such I'm ruling that the game is suspended temporarily"
He turned to address Kaidoh and Momo.
"You are directed to travel to Planet Spectra to rescue G-Force from the sinister clutches of Zoltar. Hurry back to complete your match"
"Hai"
An older woman, perhaps seventeen, stepped forward.
"I'm Trixie, and Seven-Za... I mean, President Kane got me a helicopter so that I could fly you where you need to go. Come with me, please"

"Well, One-Rover-One, I think that this should sort out everything. Now back to watching Horio. I anticipate that he will use this time wisely, now that the match has been suspended"

Trixie landed the helicopter outside Urahara's shop.
"Good luck"
Kaidoh bowed.
"Thank-you, Trixie-san"
Momo waved.
"Thanks for the lift"
A man in clogs approached the two of them as Trixie flew the helicopter away. He had a hand on his hat to keep it from blowing away. He motioned them inside.
"What can I do for two young gentlemen as yourselves"
"We need to travel to Planet Spectra, please," said Kaidoh.
"Well you're in luck. I happen to have two space-worthy transforming gundams in stock that should do you nicely. Anything else"
"We're junior members of G-Force, so we need cool uniforms!" said Momo.
"Uniforms? In my experience, G-Force just transmutes their street clothes into their uniforms. As junior members you should have received special wrist bands enabling this"
Kaidoh and Momo looked at each other.
The phone rang. Soon a man came and whispered something to the man in the hat.
"Well, it seems that Seven-Zark-Seven has another hidden camera in my shop. I'll deal with that later, but for now I'll just have to get you equipped. Fortunately his credit is good here"
He walked toward some racks, motioning to Momo and Kaidoh to follow.
"Now then, G-Force members usually dress as birds. What kinds of uniforms would you like"
"I heard that dinosaurs were a kind of bird. I want to be a dinosaur!" said Momo.
"Shut up! Don't waste this man's time by being stupid! Be something normal. I'm going to be an eagle"
"You shut up! Everybody knows that the team leader is already dressed as an eagle! Besides, dinosaurs are cooler than eagles"
The man cleared his throat.
"Well, I think we can sort this out. The other thing is that we'll need to decide which of you gets which gundam. One of them transforms into a shuttlecraft from the Starship Yamato, and the other changes into the form of a dog"

"Come on, Tiny! Put some muscle into it"
"I'm trying, Jason, but I just can't bend these bars! They're made out of some kind of metal, and they won't budge"
"Wuss"

Kaidoh stood before his gundam. It was red and yellow and bronze, and he loved it. Momo had already changed his into a shuttlecraft and was off buzzing the beach, but Kaidoh couldn't figure out how to get his to change. He adjusted his mask and tried again. Nothing happened.
The man in the hat walked up behind him.
"Oh, that one's broken. Didn't I say? I can store it for you here if you like until you can repair it. Storage fees are very reasonable"

Momo landed the shuttlecraft back at the shop and transformed it into its humanoid form. He walked it toward Kaidoh, and turned on the intercom.
"Hey Mamushi, hurry up! We need to fly off to Planet Spectra"
"Shut up"
Kaidoh run up to Momo's gundam.
"Mine's broken! I don't have time to fix it right now, so I need to travel with you. Change this thing back into a shuttlecraft and let's go"
Momo changed his gundam back into a ship.
"Your is broken? You whined so much that you wanted the dog. You were so excited. And you broke it already"
Kaidoh climbed into the shuttle.
"Shut up! It was broken when I got it"
Momo closed the hatch behind Kaidoh and turned to face him.
"Poor Mamushi, he gets his dog gundam and breaks it right away"
Kaidoh tore off his mask, and his face was turning a dangerous shade a red. Momo set the navicomputer with Planet Specta's coordinates, and the shuttlecraft launched spaceward.
"Poor Kaidoh, breaking his toy before he even had it five minutes. You know, I think I'm going to name my gundam 'Lucky"
Kaidoh grabbed Momo by the shirt of his uniform and shoved him up against Lucky's bulkhead. He pushed his scowling face close to Momo's.
"You shut up, Momoshiro. Right now"

The alarm grabbed Momo's attention. He hurried over to the control panel, slightly out of breath.
"Hey Mamushi! We're there! And there are a bunch of spaceships here! It's really cool"
Explosions rocked Lucky, and the small ship plummeted planetward.
"You idiot! You're making us crash"
"It's not my fault! I'm still learning how to pilot this thing, and those purple spaceships are shooting at us"
Lucky's automatic systems cut in, and it transformed into humanoid form. Its engines finally died, and its parachute deployed automatically. Lucky descended gently into a circle of about a hundred waiting guards.
Momo and Kaidoh cautiously poked their heads out of Lucky's smoking torso.
"We surrender," said Momo.
Two guards moved toward them.
"Throw down your weapons," said the first.
"We don't have any weapons, sir," said Kaidoh.
"What are those things you're carrying then?" asked the second guard.
"These? Oh, these are just our tennis rackets. We never go anywhere without them," said Momo.
The two guards moved their heads together and whispered to each other.
"Should we let them keep them"
"I don't know. We're only supposed to confiscate weapons. Is Zoltar here yet"
"No. Maybe we should just put them in prison"
"Good idea"
The guards straightened up, and one of them address Momo and Kaidoh.
"Okay, you can keep them, but no funny business! Now follow us"
Momo looked at the circle of guards pointing their rifles at them, and nodded.

"Mark, I hear something"
"What is it, Princess"
"I think the guards are coming back"
"Ryoot zoot deebop"
"Boy, you said it Keyop"
"I see them too, Mark"
"Thanks, Tiny. How about you, Jason"
"Yeah, they're a couple of skinny kids. Who'd be stupid enough to send kids into a place like this"
Kaidoh and Momo walked down the prison corridor and were put into cells opposite each other. The guards left.
Kaidoh looked in amazement at the famous G-Force team. He kept a respectful silence.
Momo, on the other hand, spoke up.
"Hey, you guys are pretty cool. Too bad you got yourselves captured by these losers"
"Shut up! You guys were captured after we already softened them up, so you're even bigger losers"
"Now Jason, let's be patient. Maybe they have news for us," said Mark.
"Yes sir," said Kaidoh. "We were sent here by Seven-Zark-Seven to rescue you"
"Ryoot-Zark-Ryootdoot"
"Oh I knew Seven-Zark-Seven would come through for us!" said Princess.
"Yeah? Well he did a pretty lousy job. They're in here with us!" said Jason.
"We'll need a plan," said Mark.
"Hey, it's too bad you guys didn't push the big cell release button on the way in," said Tiny.
"Which one's that?" asked Momo.
"It's the big red button just around the corner. We don't have any way to hit it, but if we did then we could get out of here and escape in the Phoenix"
Momo and Kaidoh looked at each other.
"How far around the corner, Tiny?" asked Momo.
"About fifteen feet"
"Do you think you could hit that, Mamushi"
"Only if the ball was already hit hard enough. You'll need to use your Super Dunk if my Boomerang Snake is going to work"
"Let's do it"

Zoltar finished applying the final layer of his lipstick.
"Now, to interrogate those two new prisoners"

"Okay, quietly everybody. We're going to have to get to the hanger to board the Phoenix, and there may be guards," said Mark.
Everyone nodded, and began walking on their toes. Sure enough, there were guards in the hanger deck, but they were busy playing cards and didn't notice the five fearless young orphans plus two. The team had almost made it to the ship when Zoltar entered the bay.
"Guards! They're getting away! Stop them"
The guards jumped to their feet, knocking over the card table, and began shooting at G-Force. Five of them began jumping, flying, and performing aerial somersaults. Two of them just ran like hell.
Once inside, they strapped themselves in and Tiny executed a rapid take-off, the beams of the guards' rifles bouncing off the hull.
"Well, that went well," said Jason.
"Maybe not," said Mark. "We'll need to watch out for the sentry ships"
As the Pheonix ascended through the atmosphere, dozens of spaceships darted toward it, firing missiles and laser beams. The Phoenix heaved and lurched, and explosions sounded all around them.
"We can't take much more of this, Mark!" said Tiny.
"Oh no!" said Princess.
"I knew it," said Jason.
"Ryoot zabbitt"
Momo and Kaidoh just looked at each other.
Mark sighed, and said "Well, I guess it was inevitable. Tiny, let's go to the Fiery Phoenix"
Everyone gritted their teeth and held tightly to their seats. The Phoenix burst into flame and easily outdistanced the sentry ships.

The robot cleaned one of his viewscreens.
"Well, I'm happy to report that Horio's teammates rescued G-Force and successfully made it back to the tournament"
"Wap! Wap"
"That's right, One-Rover-One! Horio didn't even have to wait for them. Someone of his year told the referee that the two people rescuing G-Force chose to default, and now the boy in the cap is playing the next match"
The robot extended his legs and looked more closely into a monitor.
"But look! Horio's drinking a cider! That's always worth watching!"