Eevee only appears as a random trophy.
As adaptable a Pokémon as any yet discovered, Eevee's evolutionary progress changes to meet the conditions of its environment. So far, five evolutionary forms have been discovered and then catalogued for this unique Pokémon; Vaporeon, Jolteon, Flareon, Espeon, and Umbreon. All evolutions have special benefits.
Eevee appears as a new Poké Ball Pokémon in Super Smash Bros. for Nintendo 3DS and Wii U. It uses the move Tackle if an enemy is nearby. If nobody is nearby, it will stand in place looking left and right waiting for somebody to tackle.
NA: This Normal-type Pokémon is as adaptable to evolution as they come, with eight evolutions discovered thus far. If you pair that potential with its adorable features, it's no wonder Eevee is so popular! In Smash Bros., Eevee will attack a nearby opponent with Take Down. Sadly, this attack isn't incredibly powerful.
PAL: This adorable Normal-type Pokémon's ability to evolve in so many different ways makes it a popular choice with trainers. When brought out in battle, Eevee uses Take Down on the first opponent it sees, but...it's not very effective. Never mind. Eevee may not be the toughest Pokémon, but it'll always be one of the cutest.