The polish (1.b4) is a flank opening, although I wouldn't recommend it.
who are the flank openings?

The Grob Attack (1.g4) is also classified as a flank opening. Not recommended though. Simple rule of thumb: if there is no (or very little) chess literature on a specific opening, it is probably not worth playing.

You mean what are the flank openings? Pretty much anything that doesn't involve an early e4 or d4. "Flank" implies that you are developing on the wings before making an advance in the center.
The most mainstream/accepted are the English (1.c4), Reti (Nf3 + c4), King's Indian Attack, Benko (1.g3), Larsen (1.b3).
who are the flank openings?