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Kasei's Gardevoir is a level 100 Gardevoir. This Was the first pokemon Kasei had, as he was given it when it was still a Ralts. It is his favorite of the three pokemon he owns, and is the pokemon he uses when battling against Gym Leaders and the elite four. He does not keep Gardevoir in a pokeball.
For more information on this Pokémon's species, see Gardevoir.