Well, you wouldn't really need a Staller, since Uxie can basically tank everything.
But if you insist:
Blissey @ Leftovers
Ability: Natural Cure
EVs: 252 HP / 252 SDef / 4 SAtk
- Softboiled / Wish
- Thunder Wave / Toxic
- Flamethrower / Seismic Toss
Note: This is a Special Tank, not a Physical one.
Flamethrower are for the ones that are Immune to Toxic.
Seismic Toss if you are playing in Showdown with that team.