Snorlax has never been useful in standard formats.
The Delta one actually saw use in the Mewtric builds a few years ago during the 2v2 Professor Cup, which in my opinion, should have taken the event.
Second, I used Snorlax, the promo fan art one, that stopped retreats to get 3rd at the Team Multiplayer Championships in 2003. The way the rules worked, it could effectively isolate one of the players out of the game by locking a baby active. Players ran Double Gust as their means of switching, and with how the rules worked, if I had Snorlax active, and no benched Pokemon, and I double Gusted say, Cleffa, active, and I declared Cleffa with Snorlax's power, it could not retreat. Than, if they used Double Gust, I could target their partner, and even if they targetted me, I had no bench. So the second either player benched a basic, they were locked out of the game unless they oddly ran non-Double Gust switching. So by virtue of rules loophole, Snorlax was arguably the best card in that format.
Snorlax, being my favorite Pokemon, needs a good card though. I'm still looking forward to the Level X and hope it comes to America, or else I'll be after a Japanese one.