Boltbeam Resttalk Cresselia is a total set-up fodder and epic uselessness. It helps with Breloom but you have bigger fish to fry, namely all of the sweepers that try to switch in on Cresselia.
Cresselia @ Leftovers
Trait: Levitate
EVs: 252 HP / 108 Def / 148 SDef
Bold Nature (+Def, -Atk)
- Ice Beam
- Reflect
- Thunder Wave / Toxic
- Psychic / Charge Beam
^Probably the best Cresselia set around imo. It's a pain to switch into really, and isn't a total set-up fodder. Cresselia doesn't have any recovery options that could fit into this team (or many teams at all for that matter), so I wouldn't worry about them. If you're going to use Cresselia, don't make it a mega set-up fodder like the resttalker is.