Blastoise could do well on a rain team. Flying types can do well under rain, especially those that learn Hurricane by level up. Noivern, Swanna, and Vivillion are some examples available in Reborn. Steel types like rain with fire moves being nerfed. Reborn doesn't have a many good steel types currently, but Magnezone is solid and as is Bronzong, which can learn Rain Dance as well. Pokemon with abilities that benefit under rain like Swift Swim and Dry Skin can also work. There are a lot of Swift Swimmers out there, one of the best being Kingdra. Armaldo and Beartic are non-water types with Swift Swim that can provide solid coverage. Jynx and Toxicroak both have Dry Skin and can provide good coverage for a rain team as well.