So I heard you wanted to use a Purugly? Well that's not an easy thing, but I would recommend this set:
Jolly Nature. Item:Leftovers
18 HP, 252 Attack, 240 Speed.
The Tricky Part of this set is getting your first Hone Claws boost, as this is difficult due to Purugly's Frailty, but once it happens the magic begins. Once Purugly has his boost, he now has now has a relatively reliable sleep move to incapacitate his victim. Then, if he hasn't already, immediately sets up a Substitute to provide protection. Once this happens he has a free turn to either kill his target or continue setting up Hone Claws; at +2 he is golden, as Hypnosis will have 100% Accuracy, and he can spam it over and over again without worrying about missing. Combined with Substitute and leftovers recovery, it will be very hard to hit him afterward, and then he can prepare a sweep with the attack boosts. While Mono-Normal is not the best way to go due to ghosts being immune, it is still quite the uphill battle for Rock and Steel Types due to the sheer number of turns Purugly gets in this way.
In a contextual manner Purugly will usually the crucial initial boost to get this set rolling as the opponent uses a status move or Purugly Blocks an incoming status such Thunder Wave or Will-o-Wisp with Substitute. Thick Fat can let Purugly take a Fire/Ice move if the opponent forgets that Purugly has access to it(Who remembers Purugly anyway?) to get the crucial initial boost. An unboosted Hypnosis is Purugly's fallback, and last resort option.