Something like this: Mimikyu is in non-busted form with a Weakness Policy {{Pokemon}} use Iron Tail! It's Super Effective! (This text won't appear I think) Mimikyu took no damage Mimikyu's disguise was busted! So does Weakness Policy activates at this point?
Because a Disguise-busting hit skips the type effectiveness check in the damage formula, Weakness Policy will not activate regardless of the move's type.
Source Hope this helps!