Choice Band Tyranitar is a fantastic partner for Shaymin; it traps and weakens or OHKOs several obstacles to Shaymin, such as Latios, Latias, Chansey, and Blissey, while Shaymin easily takes on most Water- and Ground-types that threaten Tyranitar. Scizor can do the same jobs as Tyranitar, but has more difficulty coming in against Latios and Latias; however, it has the added benefit of being able to revenge kill slightly weakened Dragon-types with Bullet Punch. Make sure to pack a strong answer to Volcarona if you use Scizor, as it easily sets up on both Shaymin and Scizor. Any Terrakion variant is an effective way to deal with Chansey, Blissey, and Volcarona, while also taking care of Ferrothorn in rain, which Shaymin cannot break through. Heatran has excellent synergy with Shaymin, defending it from Steel-, Dragon-, and Fire-types, while Shaymin easily takes the Water- and Ground-type attacks that Heatran attracts. Another useful teammate is Gyarados. The offensive sets can switch into Scizor, Jirachi, Volcarona, Blissey, and Chansey and proceed to set up, while the defensive set checks most of Shaymin's switch-ins such as Latias, Volcarona, physical Dragon-types, and Scizor. Last but not least, a Rapid Spinner is always appeciated as a teammate, because Shaymin tends to get set up on by popular hazard setters. Tentacruel is the best option for rain teams, while Starmie is superior for sand and weatherless teams.