>>44954712Black 2/White 2 is a sequel, not a remaster. If you don't want to play the same region twice, read a synopsis of the first games so recurring characters or plots don't leave you in the dark.
X/Y is... tolerable at best. Easily the worst of the bunch listed here. It's the only way to experience Kalos, so you could give it a shot if you really wanted to.
USUM invalidated the base games. Skip over SM and go right to USUM. People will shit themselves over the plot for being "worse" and therefore not worth playing over the originals, but you shouldn't be prioritizing story over content when it comes to Pokemon. Besides, the story isn't that much worse than what it was already. Lillie sucks; try your best to ignore her.