Although STAB Return is really powerful, OU is so littered with Steel types and Gengar that being locked into Return can have some major repercussions, and leave Snorlax as set up fodder. The reason Snorlax is so successful in UU, is due to the plethora of Fire types which Snorlax walls comfortably, and the lack of Steel types that resist his STAB. Even in UU however, a Curse set is usually always preferred. There are so many things in this meta game that out class most of what Snorlax does in OU, and I find it hard to believe that Snorlax was actually rated C-Tier. Don't get me wrong, I love Snorlax. But there is so much in this meta game that can really hurt Snorlax, and at the same time, out class most of his prominent sets. His ability seems to be the only thing going for it in OU, since it can come in on Fire types quite easily. Still, he's slow as molasses, and can often times be set up fodder for Steel types like Skarmory and Gengar who can come in on a CB Return and set up a free Substitute. I actually think Snorlax should be D-Tier along with his friend Chandelure. I just don't feel like he fits well in C-Tier, because Slowbro, Slowking, Vaporeon, Gastrodon, and Cresselia are arguably much better walls, and find it much easier to succeed in the OU environment.