Presuming "pony" means "crap" in this irritating thread title, and presuming the Beatles had the same inborn talents no matter where they were born, I don't see any reason to believe they would've produced an inferior body of work - most of their influences were American, after all. Whether they would've broken as huge in the USA as they did without their delightfully exotic English accents and European haircuts and fashion sense seems less likely. But they surely could've been as big as The Beach Boys - their only logical comparison in that odd assortment of performers mentioned.
As for ...