If he uses Flare Blitz before he takes damage he cancels his own Focus Sash, if he takes damage and hangs on with Focus Sash he kills himself with his own move. That set will never work sorry.
I was going to put either hypnosis or Fire Blast their instead or I was going to attach it with expert Belt. Since it is fire type, Hp Electric seemed like an ideal choice. Ice or grass may be another choice for stuff like dragons, swampert, grounds. Not really sure though.