Ptera: Unconventional, but I like. Mamoswine would 2OHKO with Ice Shard, but the HP is enough to survive, call in some rain, and then get outta dodge. The rest is unequivocal, so the only thing to do is watch out for other lead Aeros or lead Scarfers.
Giga: Nothing to say, looks great. While I'm sure you prefer Surf, Hydro Pump was the best move to choose. And I agree: a Rain Dance team is incomplete without a Kingdra in it.
Hoss: Cute name; only thing I would suggest is to give it a Focus Sash, and be sure to use it against something without priority moves.
Omi: Looks good to me.
Blaine: I would say keep EQ, as it will hit Magnezone and any other Steel-type, as well as any Fire-type that ends up switching against Bronzong (regardless of Rain Dance). Besides, EQ has nice coverage and you never know in which situation you may end up where EQ might be a lifesaver.
Zapdos: No nickname for the big thundering bird? Anyway, the set works with the overall team, but it does feel like it was jammed in there as filler--not that you should stop using it if it has worked for you.
If you're still wanting to change it, the only PKMN that comes to mind that would work as both Wish passer and Rain Dancer would be Gardevoir. The moveset could also include both Screens with Light Clay as the held item, or just one Screen and Psychic for STAB and all-around coverage. A Timid nature should work with maybe 252 EVs in HP, 200 in Speed, and the rest in Sp. Defense--you could very well go for 252 in Speed, though. Chansey and Hypo could also be candidates, but Gardevoir is obviously faster.
Those would be my two cents.