Oh really?
Here's the scenario. Your opponent has out a Haxorus, and you a Chandelure. You withdraw Chandelure and send in a level, let's say, 19 Yamask. Haxorus OHKOs Yamask with Outrage and acquires Mummy. Then you send in Slaking. See where this is headed? Ordinarily, Slaking would hit Haxorus on the inevitable switch with Pursuit, acquiring Mummy, but since Haxorus is locked into Outrage and unable to switch out, Slaking instead opts to OHKO with Slash. Either way, the turn ends with Slaking minus Truant and ready to sweep. I know this works, because it's happened to me. And my Slaking wiped out the rest of the opponent's team, FYI. My finest Random Matchup moment.
Yamask still sound horrible? And before you mention the possibility of Yamask's immunity to Normal and Fighting screwing things up, I have two words to say to that; Ring Target.