Before we start the story, let us get familiar with the charachters:
Boom: A young female trainer who is very strong and has defeated three leagues; Hoenn, Unova and Kalos. She is very caring for her team. If they are ever injured, she is at their aid in an instant. She treats Pokémon with great respect, and shames anyone who uses them as tools.
Bomb: Boom's autisic brother. Even though he is younger, he is even stronger than her sister. He is a dedicated member of Smogon University, and takes competitive battling seriously, but will attend Booms adventures if he is needed. Most of the time he cannot take care of his main team, so they are left in his sister's care.
Blitz: A shiny Latias who is very loyal to Boom and will always obey her commands. She usually helps take care of the others, especially when Bomb is away. She is very organized, always on track of time. She is basically Boom's second-in-command. She often attacks head-on in battle, and Recovers all her HP back when needed.
Emerald: A therian-forme Tornadus who often sits back and watches the others. Another loyal member of Boom's team, he is serious, usually showing no emotion, but he will if he has to. He is the peacekeeper of the team, usually assisting Blitz in breaking up fights. He never lets his guard down and he always keeps his cool in battle. He will even risk his life to protect his comrades.
Lunara: A sweet and playful Cresselia who is always bound to make new friends. She is very extrovered and optimistic, always assuming the best of things. However, in the face of great danger, she is unsure and scared, often hiding if something is pursuiting her. She has a huge crush on Emerald. She heavily relies on her Psychic attack to keep enemies away.
Blade: A brave and happy shiny Gallade who love a challenge. He is always socializing with Pokemon he meets. If someone wants to battle him, he never turns down the offer. He likes to stay out if his Pokeball to enjoy the places Bomb goes. He is swift and agile in battle, striking fast and consistent blows.
Sapphire: A very calm and modest shiny Gardevoir who always sticks by Boom's side. She is almost like a daughter to Boom. They take good care of each other, and they stick up for one another. And its no secret that Blade and Sapphire, despite being on different teams, are almost like a married couple. Sapphire often freezes the enemy with Psychic and either squeezes their body or thrashes them around.
Hyalite: A fun-loving and naive shiny Hydreigon that Boom received as an egg on her 10th birthday. He is very sweet and affectionate, and is gentle around strangers. He has corrupted Boom's tabtop more than once because of scam ads. She installed an adblocker to prevent it in the future.
It all started when two sibling trainers, Boom and Bomb, sat down with their friends at their junior high lunch table. They all shared a strong bond with each other, which cannot be severed by even the sharpest of insults. They would often talk about battle strategies and newly discovered Pokémon. Suddenly, one of Boom's friends shouted out a dare to her:
"I dare you to defeat Kyurem!"
The whole table went silent.
"Come on! You have four legendaries on your side! You can do it!"
Boom tensed up a little. "Well first of all, I have three Pokémon who are weak to Ice-Types. Second off, some of my Pokémon aren't even lv. 50 yet, and you expect me to defeat a lv. 70 or 80 ice dragon?"
The friend nodded in acknowledgement. "Touché. But even then, you still have one lv. 100 you can use as a last resort! Come on, use the Palkia! Use the Pearl!"
Boom paused in thought for a moment and then replied. "I want to have a fair fight with Kyurem. I will not use Pearl."
Everyone's faces went to surprise. "Well then, who will you use?"
"I will use my brother's Gallade. Bomb, is it alright if I borrow Blade?" She turned to her younger brother.
Bomb paused, then nodded in agreement.
"Alright then, I will set out tomorrow to the Frozen Cavern. However Bomb will need to come in case Kyurem decides to fight dirty.
On Friday morning (weekends are 4 days long in Unova) Boom and Bomb packed warm clothing and some snacks before setting out to Kyurem's home. Their friends waved goodbye to the intrepid trainers as Boom soars away on her Latias and Bomb on his Latios. In about a half-hour, they arrive in northern Unova's majestic mountain range. The tallest peak is where the Frozen Cavern, and Kyurem, reside.
Once they arrived, they put their snow gear on and slowly walked into the cave.
Once they were in the middle of the cave floor, Boom took a deep breath in, and then called out Kyurem.
"Kyurem! I am here to challenge you to a match!"
There was a moment of silence. Suddenly, an icy cold shaft of wind blew out from a large hole in the cave. It whirled around the walls of the cave like a tornado. Bright yellow eyes flashed out from the darkness.
"Who dares to challenge me!?" A deep, booming telepathic voice roared out.
Kyurem reveals its full form. It approaches Boom until its head is only a meter away from her face.
"Well, well, what do we have here? A child fleshling? How pitiful. Kyurem will show you who the strongest one in Unova is."
Boom smirked. "Look out, big guy. I'm a hella lot stronger than I look. And I got my brother to back me up in case you fight dirty."
Kyurem raises its head up. "Is that so? Show me."
"Oh, I'll show you." Boom sent out her first Pokémon, Hyalite.
"Now, for the first part of the battle, I'll be easy on you. But with every knockout I sent out a stronger Pokémon, so be careful."
The battle engages, but Hyalite is easily defeated by Kyurem's Ice-Type moves.
"Ha, that was as easy as taking a nap!" Kyurem bellowed out.
"Alright then, 1 down, 5 raring to go!" Boom sent out Sapphire.
Even though Sapphire is probably only as tall as Boom, her Psychic-Type moves can lift a 500-ton boulder. She easily carries Kyurem into the air with her Psychic attack, thrashing it around the room before finally letting go. But Kyurem simply shakes it off.
Sapphire is stunned, but keeps her cool. Kyurem fires a Dragon Pulse, but it does not affect her, as Sapphire is a Psychic-Fairy type, and Fairies are immune to Dragon-Type attacks.
Kyurem stumbles back in shock. "How? How can an inferior being not be affected by my dragon attacks? Well, I must get this threat out of my way." He launches a Glaciate attack, freezing Sapphire. He fires an Ice Beam, and Sapphire is out of the game.
Boom is surprised that her Gardevoir did not defeat the king of dragons. She sneers and sends out Blade.
"Fighting type moves are super effective against Ice types, so keep your guard up, Kyurem. Blade is very fast."
Blade almost skates across the icy floor, circling Kyurem before using Close Combat. He almost scores a direct hit. Kyurem has about ¼ of its HP down by now.
Kyurem collects itself and uses Glaciate again, freezing Blade.
"T-Twice in a row!?" Boom was shocked. "What are the chances!?"
He does the same thing as last time. He fires an Ice Beam, and Blade is out. Fierce battling goes on for the next half hour, until Boom is down to her last Pokémon. Both Kyurem and Boom are panting. Battling doesn't wear out just the Pokémon, but the trainer too.
"Alright then, I guess I will unleash my full potential." Boom sends out Blitz.
"Now Kyurem, want a little demonstration on Mega Evolution?"
Kyurem backed up in confusion. "Mega… Evolution? Is that something from those crazy Kalosians oh so far away?"
"Yes. I'll show you."
Boom revealed a rainbow coloured stone embedded in a bracelet. It had a symbol in it that represented Mega Evolution.
"This is a Key Stone. The trainer hold this stone. The stone the Pokémon holds is called a Mega Stone. In this case, Blitz is holding the Latiasite. The trainer activates the two stones, and a new power is unleashed."
Boom breathed in and stood tall.
"Now Blitz, beyond evolution, Mega Evolve!"
Boom activated her Key Stone. The stones reacted and were encased in a blinding light. Four beams shot out of each stone, connecting at the tip. Blitz was cocooned in a bright energy. Her shape and colour changed. The cocoon exploded apart and evaporated, revealing Blitz' true power. Her appearance was more streamlined. She went from shining gold to a bright sparkling green. She was bigger and more powerful.
Boom snickered. "Now we'll see who the strongest one in Unova is."
Blitz fired a Dragon Pulse at full Power, scoring a direct hit in Kyurem's face. A critical hit! ¾ of Kyurem's HP is gone.
"Well, I should show my full power as well."
Kyurem absorbs strength from the ice and transforms into White Kyurem!
"This is one of my three forms. I will use this one for the remainder of the battle."
Boom smiled. "Seems fair."
The battling was intense, but Blitz is defeated.
Boom looks up at Kyurem and smiles. "This is the first time I have lost a battle in a while. I am genuinely impressed. But prepare for when I come back. I will be stronger, and that's a promise."
Boom and Bomb soar away on Bomb's Latios, who is Mega evolved to fly faster.
Boom chuckled a little. "Well, better get training, Bomb!"