First You must done task:
1. Unlock all character
2. Unlock Battlefield
Done well, how time thing did.

Suicune: Beat All-Star, use Mewtwo at three time.
Entei: Beat All-Star with Suicune
Raikou: Beat All-Star with Entei
Arcanine: Beat All-Star, use Raikou
Ninmetales: Beat All-Star, use Arcanine
Flareon: Beat All-star, use Entei
Jolteon: Beat all-star, use Raikou
Vaporeon: Beat all-star, use Suicune.
Delcatty: Beat all-star, use Mewtwo
Blaziken: Beat all-star, use Suicune
Swampet: Beat all-star, use Raikou
Sceptile: Beat all-Star, use Entei
Latios: Beat all-star with all character.
Latias: Beat all-star with Latios.
How to allow to use ten character into battle. You must unlock 6 character of Pokemon. 4= can for player. 6= Foe only. Only in V.S. Mode.