Mega Pokémon
From PokéHeroes Wiki
Only Pokemon which can mega evolve in Pokemon X and Y can mega evolve on Pokeheroes. This does not include Poke heroes event Pokemon. Only a Pokemon with a Mega Bubble icon on it's summary page is able to evolve.
How to get Mega Pokemon
Only Pokemon on this list are capable of mega evolving.A Pokemon can randomly hatch out from a normal egg with a 'Mega bubble' on it's summary page.