Oh, how I love troll sets. You could try this-
252 SpDef and HP, Calm nature, 4 Def.
Fire Spin traps the opponent for residual damage, which is nice for a Pokemon you're trying to stall with. Will-O burns to cut attack and do more residual damage and Substitute and Protect help Wish heal Braixen to give it some free time to do whatever it wants or needs.