I'd disagree with some of lilouon's suggestions...politoed and tentacruel are 100% necessary, but there are some others that would come above skarmbliss imo. SpD Jirachi, Bulk Up Toxicroak, Amoonguss, Celebi, these are going to be your best choices. Not only do these get sweet abilities/benefits from rain, but their typings offer great resistances to what a rain team needs. SpD Jirachi is probably a 3rd required poke for dragons but you'll still need something to handle garchomp or physical attackers, but Jirachi works wonders. Spinblockers in general aren't that necessary, because spinners are usually used for removing SR for support on volcarona and friends, and many teams won't be too wary about keeping spikes off more than stealth rock. Beating the setup sweepers is more important than beating the spinners to keep hazards.