Right. Crunch lets you maul slower WoW users, possibly before they get a burn off. The unpredictable part of Mega-K is which 4 moves it ends up with.
Although, for example, if you can survive that Sucker Punch and use Weakness Policy, a +2 Sacred Sword WILL slash Mega-K into knockout territory. Go with Sacred Sword, take the Sucker Punch on your Shield Form, get the +2 from Weakness Policy, KO Kangskhan with +2 Sword, and you're +2 for whatever's next (likely a Sneak if it's fast, or Sword/Shadow Ball if not). And being slow, odds are it'll trigger it if they go Earthquake as well since either way, Mega-K will go first.
It's one of those cases where Weakness Policy Aegislash can gank the monster before it goes berzerk, if you get it in before the thing PuPs up. But that's prediction games- if it hits you on the switch in, it wins anyway. If you switch in on a PuP, you're almost guaranteed with Mega-K to see a trigger for WP and can slap it out with a +2 Sword. If it's EQ, you're getting 2HKO'd by the second hit before you can OHKO it.