Now that ORAS is out, and with it, new move tutor moves, Slurpuff will wreak havoc due to only one move it gets: Drain Punch.
Now it will no longer be walled by Steel- and Fire-types, unless they're the Honedge line or the Litwick line. Of course, Poison-types prove a massive problem, so it's a good idea to get rid of all the opposing Poison-types before bringing Slurpuff in to sweep.
Slurpuff @ Sitrus Berry
EVs: 252 Atk / 252 Spe / 4 HP
Slurpuff gets a lot of opportunities to set up Substitute, mainly on slow status users like Lampent or Gourgeist. It can then proceed to Belly Drum and wreck teams.