Game-Breaker: All of the bosses. Goodman is so far into this territory that he isn't allowed to have a tag partner (if you're good/lucky enough to unlock him).
Unexpected Character: In a game full of Neo-Geo All-Star cast, who would expect a somewhat forgotten character like Lee Pai-Long, who hasn't seen a playable appearance since Art of Fighting 2...or really, Kisarah Westfield from an obscure game like Aggressors of Dark Kombat!?
Nevermind them, who would've expected Cyber Woo to show up?!