A name of that opening (1. b4 a5)


Why not 1...Nf6 remaining flexible? 1...e5 is a great move but black is likely to be very prepared for it so only go into the 1...e5 lines if you've studied 1.b4 before (lol that sounds alike ^_^ )
Intuitive principled chess is what the unorthodox guys are banking on you playing, and by definition is what you should theoretically play. Thus, go into their mainlines if you know the theory, try something a little unexpected but still a reasonable reply (e.g., 1.f4,c5!? 1.b3,f5)
1...a5 looks playable enough but I think there may be better options objectively. 1...Nf6 to be safe or 1...e5! if you understand the Polish enough to deal with prep.