It was looking less and less likely that these guys would have names, so I felt I had to make my own. If you have evidence otherwise, please tell me in the comments below.
Blue unicorn is most likey Bow Tie from g1, as Hasbro likes to reuse ponies, especially given that Cha Cha is literally in this set, the white unicorn definitely looks like few existing ponies and the pink one looks like Sunshine Smiles.