>>45420052>>45420121Sableye would honestly be a downgrade. Fairy coverage is everywhere, and Sableye REALLY wants those Prankster Wil-0-Wisps and Recovers. It's generally better than Shedinja, obviously, but essentially is just that, an improved Shedinja that doesn't instantly die to weather and hazards. The recovery almost doesn't matter, because anything that can actually hit Sableye is probably going to kill it in one hit. Sableye's only neat trick is Magic Bounce, to send status back.
Spiritomb would be much more interesting. Spiritomb is decently bulky enough that just hitting it with a Fairy move once isn't enough to kill it, meaning you can honestly build a pretty decent wincon out of it, and a catch-all check to setup sweepers, similar to Clefable, even getting Psych Up to piggyback those boosts and threaten whatever comes in on it. Pain Split gives it a way to recover and take bites out of switch ins, Curse+Protect means the opponent's switch in immediately takes 50% damage for trying, you can also cripple it by Tricking it some bullshit or putting it to sleep with Hypnosis. Spiritomb also has okay offences; it's not oneshotting anything, but just spitting out Shadow Balls isn't a free switch either.
Spiritomb would be a definite step over Shedinja, or hypothetical Wonder Guard Sableye, because it isn't just a wincon, it's a wincon that can both support itself, and a team if you build smartly. It's not free, since Fairy coverage is pretty damn common, as are ability nullification, indirect damage, ect, but it can absolutely be a functional component of a team, nut just a gimmicky wincon.
I think it's in a very uncomfortable position for the OU meta, and would probably be tiered as BL or UU, but would still see fairly regular use in OU.