The Legendary Titans or Regis are canidates for Pokeball Pokemon in SSB4.
Each titan brings a unique twist in the arena. They have different, powerful attacks.
Regirock uses Rock Slide. In this attack, he summons a mountain. Then, he slides down the mountain. When he lands, he makes a huge shockwave that damages people.
Regice uses Blizzard. Depending on the direction he is facing, he summons a huge snowstorm that can combo hit opponents and freeze them as well.
Registeel uses Flash Cannon. He fires a large laser depending in the direction he is facing. The laser combo hits opponents and even paralyzes them.