I have an Unfeazant with Facade, I gave it a Flame Orb and Challenged the Elite four.When the user is burned Facades power doubles, but my Unfeazant can't cause more damage than the 1/4 of the foes HP. Why ? It's attack is 256.
Okay,i know the problem.. Generally, if a Pokémon is burned, it will lose a set amount of HP every turn, and its damage dealt by Physical moves will be halved.So give it a toxic orb and then it will do double power.Your idea should work then.
This is what Bulbapedia says when using facade:
Facade inflicts damage. Its base power doubles from 70 to 140 if the user is poisoned, paralyzed, or burned. Burn's effect of lowering attack is still applied, unless the user has Guts.