Sneasel is O-K as a Cleanner and ocassional Revenge KOer, but that's pretty much all. Choice Scarf and Priority are so common that Sneasel offen fails at clean, anyway, so, there's not too much use, but he can deal good damage to the opponent's team and force some switches with the correct use, but it's weakness to Stealth Rock means you'll just be able to do that 4 times at most on the game without the help of a spinner.
But, hey, he can switch-in against a Psychic and threat... with Pursuit or Bite... not even enough to OHKO Musharna or outspeed Choice Scarfer Gardevoir, but that's still something, I guess. Taking in account Sneasel is already outspeeding almost everything without a Choice Scarf, then you can forgoe it's speed, and give him some of special bulky (he can't take physical attacks), Life Orb, and Sword Dance, and as long you keep him far from Choice Scarfers and priority users, you'll do really great.
I love Caterpie, he's a so adorable little bug! ♥ (Also, sorry for my English, I'm still learning it and I'm not a native speaker).