>>31201322Pokémon-EX
An EX Pokémon is a Pokémon surging with Evolution Energy, the common name for the inherent energy found in all Pokémon.
During an EX-surge, a Pokémon's power greatly increases, and it may even change Type or Evolve beyond its current form.
Mega Evolution is a form of EX-surge, where a Pokémon reaches a temporary higher form of Evolution in the heat of battle. Typically, this can only be accomplished by highly disciplined trained Pokémon, though it has rarely been documented even among Wild Pokémon defending their brood or tribes.
It has been theorized that Type-variant Pokémon are created when Pokémon naturally undergo an extended EX-surge in response to extreme conditions outside their normal environment.
In gameplay terms, all that shit up there is just lore you'd get from talking to NPCs and reading bookshelves.
EX Pokémon would just be an excuse to turn Legendary Pokémon (and certain Trainer battles) into superbosses by giving them stat boosts and cool Abilities or other battle effects. Basically a combination of Mega Evolution (without the form change) and Totem Pokémon.
Actual Mega Evolution also wouldn't require a held item and you'd be able to do more than one per battle, but there'd obviously be balance changes to accommodate that. And I'd probably just rather leave Megas out and balance regular Pokémon well enough that they're unnecessary.
Mostly I just wanted a catch-all excuse for all of these things outside of the shitty lore that the actual games give.