Gundam exia vs unicorn Gundam which one would win?

Unicorn will swoop the floor with all those techs and weapons. You got the destructive Beam Magnum, Shield Funnels, Beam Tonfas, and the NT-D mode that enhances its performance significantly. Added with the Newtype hax, it's currently one of the strongest unit in Gundam-verse.

Exia, OTOH, were pretty much a standard close-range unit with lots of swords. It does has Trans-Am, but it was only available for a limited time, while NT-D can go permanent mode if the pilot's will was strong enough.