Now on account of Gemini it would be two companions but in one(Like the ice climbers in super smash bros.) So it would be two people(I think something small, like the lamb farmers in mooshu) but one companion. A super hit would be one jumping on the others shoulders and them falling on the target.
I like the idea of astral companions, but they'd need a twist. I suppose making them into little Pirate101 characters is quiet a twist, but something more, like Leo would be... on fire or something, and Cancer would have attacks based on water.
I like this idea... expand on it a bit more and ye've earner yerself a Yar.