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For Tentacruel, I have a few suggestion. Since PokeBanks is already out for awhile, why not give Tentacruel the set of Barrier, Giga Drain, Rapid Spin and Toxic/Scald/SludgeWave.
You gotta check out UU Jirachi. Its not GP ready, but I feel bad for whoever has to GP it when its ready. Too long. I'm going to feel so bad for whoever does it.