PKMNB0Y has the right of it, though a different interpretation than myself. I basically see GER as an absolute, perfect defence. People exaggerate how powerful it actually is, but it really only exists as a perfect counter (via Deus ex Machina) to Diavolo's ridiculous Stand.
Honestly more troublesome is what Gold Experience normally gets up to, which smacks me strongly of Araki making shit up as he went along with Part 5.
Anyway, I really want to play a Stand User of some variety, but ones that would interact well on a multiverse scale are very often ones that are overpowered or seemingly so. Weather Report could be fun, but I'm not far enough into Part 6 that I feel like I would do him justice. Funny Valentine would fit in perfectly with the Multiverse setting, but see previous. Hm....