Well if it only has one quick move (as is the case with Vaporeon) and that's how it deals damage (high DPS Water Gun) then obviously IVs are more important cuz every one is going to have the move.
But yeah you want the specific move sets which are better so that's why i dont Power Up before you Evolve.
I wouldn't be Transferring good IV pokemon though. Anything 80% and below you can if the move set is bad but once you start talking higher 80's or 90's it's going to be a good battler