Feint attack against a baby.

[Haymaker]

Well if I do a feint attack against a baby with still has the flipping rule, do I still have to flip. I think so but I'm not sure.

[BJJ763]

You flip for the Baby Rule whenever you attack your opponent's Active and that Active is a Baby Pokémon.

[Polalion]

For any attack, if your opponent's Active is a Baby, you flip, even if you don't do damage.