Ay will blitz his clones. All swapping places with clones does is prevent the real Tobirama from getting hit, but will still end up sacrificing his clones in his place. Also FTG swapping with clones is slightly slower than the basic FTG, so if Ay blitzes at ridiculous speed, the clone or real Tobirama won't be able to teleport in time to avoid his attack. This is full intel we're talking about, Tobirama wouldn't be so stupid to waste chakra on multiple clones, especially when using FTG with clones is slower. He can't afford to be slow at all against Ay, otherwise he'll get hit. Swapping places with clones is a very bad tactic in such a fight as this to be honest.
Ay has tailed beast chakra. Using multiple clones will wear out Tobirama much faster than v2 will. Also there's no proof of how much chakra FTG uses, I've always believed it takes quite a lot of chakra, but since both users use a lot of chakra, it rakes less. After all, it does take 3 Jonin to use.