Mewtwo
Suicune
Electirizer
Rhyperior
Steelix
Rayquaza
Moltres and Charizard don't need to go in, since Rayquaza replaces them, and Blaziken is Fire/Fighting, unlike Entei, who is only Fire. But Entei also has all higher stats than Blaziken except for Sp. Attack.
Yeah, either Blaziken or Entei. Right now my Blaziken is at a higher level with better attacks, but of course that could change.