If you want a purely toxic staller, definitely Umbreon. He has fantastic defenses, a way to cure himself of status, and reliable recovery. I'd go with Toxic/Wish/Protect/Heal Bell or Payback.
However, if you want a Pokemon with higher attack, Drapion is the way to go. He can stall out reasonably well while still doing damage with his STAB attacks and stopping the opponent recovering with Taunt. Unfortunately he doesn't have a way to regain health apart from Rest, so in my opinion Umbreon is still the better choice.