To achieve Mega Evolution, a Trainer must simultaneously possess a Mega Stone corresponding to the Pokémon and a Key Stone.
A Mega Stone only works when held by its specific Pokémon species. For example, to Mega Evolve Charizard, it must hold either a Charizardite X or Charizardite Y; otherwise, it will have no effect.
As for the Key Stone held by the Trainer, the requirements were far less strict. You could just pick one up off the ground and use it.
Driven by the anime and games constantly ignoring their own lore, Professor Sycamore's Mega Evolution research could be considered the biggest "academic fraud" in Pokémon history. Iconic scenes where trainers Mega Evolved over a dozen Pokémon simultaneously without any bond, Pokémon Mega Evolving through their own berserk will, or even forcing an opponent's Lucario to Mega Evolve were too numerous to count.
Therefore, even though cyber-Steven only gave him a Latiasite, Hakuya quickly figured out a solution.
"Meowha~"
A moment later, watching her Trainer step out of the cave and casually swipe a Key Stone off a passing little girl NPC, Floragato opened her mouth, her initially confused expression instantly replaced by utter dumbfoundedness.
—Is my Trainer's ability actually 'Pickpocket'?
"I didn't expect it to fit so perfectly~"
Looking at the Mega Bracelet now strapped to his wrist, Hakuya smiled.
He finally understood why so many Trainers eagerly rushed to join Team Rocket.
—Randomly gifted items are nothing compared to the thrill of robbing them from these unscrupulous NPCs!
Given the time constraints of the randomized world, testing out his newly acquired Mega Evolution would have to wait until they returned to reality.
[Are we going to the school's battlefield next door?]
Back in his room at the dormitory building, Hakuya glanced at the Corviknight wall clock, which read 1:00 AM, and then out the window at the pitch-black night sky. Latias sent a questioning psychic telegram.
Knowing she was about to gain a new power, the tsundere little jet plane tried to maintain a facade of calm indifference on the outside. Inwardly, however, she couldn't wait to be thoroughly 'used' by her Trainer.
"No, let's head a bit further out."
Hakuya rubbed his chin, pondered for a moment, and rejected the little jet plane's proposal.
Although the Trainers' School next to the dormitory had a reasonably sized battlefield, he worried that the little jet plane's destructive power would increase too much after Mega Evolving. If she lost control, she might accidentally level the entire school. After weighing the options, Hakuya ultimately decided to find an empty clearing in the forest on the outskirts of the city.
Because it was so late and the location was remote enough, there were no Trainers camping nearby and no large colonies of wild Pokémon. They could let loose completely.
"La-woo~"
Latias spread her wings and hovered in mid-air, curiously watching her Trainer's actions.
Unlike evolutionary items like Thunder Stones or Water Stones that vanished after use, Mega Stones and Key Stones were, in a sense, more like reusable accessories worn on the body.
For instance, Steven's Mega Stickpin, Maxie's Mega Glasses, Zinnia's Mega Anklet... Hakuya ultimately chose to use a special cord to string the Mega Stone into a delicate, compact necklace.
"Alright, we're ready to begin~"
After ensuring the Mega Stone necklace was securely fastened around Latias's neck, Hakuya raised the Mega Bracelet on his wrist.
The key to Mega Evolution was to feel the energy contained within the Mega Stone, and through the mutual feelings between Trainer and Pokémon, draw out this massive power and trigger a resonance.
"Respond to my heart, Latias! MEGA EVOLVE!"
"LA-WOO—!!!"
The moment the Key Stone was raised, the Mega Stone necklace around the little jet plane's neck erupted with a brilliant light like stardust.
Immense Dragon and Psychic-type energy was unleashed, sweeping through the entire forest like a violent storm.
Immediately after, chains of energy extended from the Key Stone in the Mega Bracelet, perfectly linking with the torrents of energy pouring out of the Latiasite. The bond between Pokémon and Trainer became the crucial anchor needed to control this overwhelming power.
An all-consuming gale descended!
"Meowha~"
Accompanied by a clear, resonant dragon's roar, Latias tucked in her forelimbs. With a beat of her wings, she turned into a shooting star and shot straight into the clouds.
The hurricane whipped up by her high-speed flight triggered an unprecedented disturbance throughout the forest.
The sea of trees surged like the tide. The muffled thuds of tree crowns crashing together intertwined with the shrieking whistle of wind cutting through the leaves. When the gale reached its peak, even the moonlight seemed to tilt, drawing long streaks of light across the trunks before shattering into thousands of pieces as the branches swayed.
"Her speed is noticeably much faster than before~"
Hakuya watched the silhouette of the Mega-evolved little jet plane tearing across the sky and revealed a thoughtful expression.
Besides being faster, there was also...
"Wait, is that Beads of Ruin?"
Noticing the cluster of snow-white magatama beads orbiting around Latias, Hakuya cried out in shock.
At the same time, the Mega little jet plane's status panel popped up.
[Mega Latias]
[Type: Dragon/Psychic]
[Gender: Female]
[Level: Lv 25]
[Ability: Beads of Ruin (The power of the Pokémon's ruinous beads lowers the Sp. Def stats of all Pokémon except itself.)]
[Moves: Charm, Stored Power, Helping Hand, Recover, Confusion, Draco Meteor, Surf, Tailwind, Dragon Breath, Chilling Water, Agility]
In her Mega Evolved form, her original [Contrary] ability wasn't retained. Instead, it was randomly replaced with [Beads of Ruin].
This was the signature ability of the ruinous Pokémon, Chi-Yu, from the original games. Its effect upon entering the field lowered the Special Defense of all other Pokémon on the battlefield. It was an incredibly powerful ability, arguably on par with [Contrary].
"Hmm... it feels exactly like the lore says. Mega Evolution not only boosts a Pokémon's power but also places a significant physical toll on the contracted Trainer." Hakuya nodded thoughtfully. "No wonder Trainers can only Mega Evolve one Pokémon per battle in both reality and the original games."