Saying Sableye sucks is pretty narrow-minded. I had a rather glaring weakness to physical landorous/CB Terra/Luke, added Sableye to my team and patched it up very nicely.
Also, barring the one or two Guts mons that you see around and fire types you can literally solo teams that rely on strong physical attacks with Sableye once you remove the fire types.
Sableye needs to get more usage, it along with a couple other UU gems just don't see as much play as they really should. I will confidently stand and say that Sableye just ruins the majority of HO teams. Scizor after a burn fails to even 3HKO sableye allowing ample time to recover the damage. Most spinners cannot hope to break through Sableye making it a very reliable spin blocker. Combined with a bit of poison and fire-killing support this thing can prove to be impassable for a lot of teams. If you pair it up with SubDD Nite then many teams can find themselves in a simply un-winnable position once their mons have been burned/poisoned.
The set I run is:
Sableye @ Leftovers
Ability: Prankster
Nature: Bold
252 Hp | 252 SpD | 4 Def
- Substitute
- Will-O-Wisp
- Taunt
- Recover
Bold is there to ensure scizor is never able to score a 2HKO with bullet punch through a burn (who could otherwise come in and BP once before being burned and once after for a possible although unlikely 2HKO), and to ensure that CBTerra is only able to score around 50% on a max roll through a burn, allowing you to PP stall stone edge. The rest is to maximize bulk on the special end, so things like a LO starmie using surf over hydro pump can be stalled out with LO recoil and burn.
It requires good team support to work well, but things that force a lot of switches, good hazard support, and especially good poison support and one or two other solid walls will form a very solid defensive core for any team to work with. For those interested, try a bulky DDNite and bulky Heatran with toxic support and watch the rage quits roll in.