Quoted By:
>inevitable speed drop
>bad defensive typing
>reliant on abusable priority like Extreme Speed and Sucker Punch
>no Double-Edge and you lose to Unawares
>no Sucker Punch and you lose to faster Normal resists
>no Throat Chop/Crunch/whatever and you lose to Steel phazers and Sub Gengar
Despite all this I actually think it might be viable on certain archetypes like Screens HO and maybe Trick Room, but the fact that it /needs/ that support means it likely won't get enough consistent usage to be OU.