You might as well use Ludicolo for rain stall on an OU rain team. Only Swift Swim + Drizzle is banned in OU, but Rain Dish + Drizzle is allowed. No point wasting a moveslot to set up Rain Dance.
Ludicolo @ Leftovers
Ability: Rain Dish
EVs: 248 HP, 204 Sp. Def, 56 Speed
- Leech Seed
This is kinda like a Gliscor stall set, except with Leech Seed instead of Toxic. Exeggutor makes a similar Sun stall with Harvest or Chlorophyll.