Super Smash Bros. Ultimate DLC: 7 Pokémon We Need To See
4. Gardevoir
Gardevoir is a fan favourite, with a lot of potential. Coming with an awesome array of moves such as teleport (which would make a great recovery) and Moon Blast (which would make a great special attack), Gardevoir also has endless possibilities for a Final Smash.
Mega Evolve, getting help from the Gardevoir family of Pokémon (Ralts, Kirlia and Gallade), creating a mini black hole as mentioned numerous times in the Pokédex - take your pick.
Gardevoir's potential alternate costumes could be blue shiny, or a colour scheme based on shiny Mega Gardevoir - either would both be awesome choices.