Sableye has two abilities that alter its speed priority, Stall and Prankster. This allows for some easy mind games and unexpected battling strategies that give Sableye great flexibility.

Sableye @ Mental Herb

Prankster w/ Jolly or Adamant nature

252 Attack / 252 Defense, 252 Special Defense, 4 HP

Taunt

Will-O-Wisp

Swagger / Recover

Foul Play / Knock Off

These two sets are your standard Prankster Sableye sets. The EV spreads are split depending on the move set you plan on running. If you'll be using Foul Play and Swagger, the EVs in defense are more useful as it'll help lessen the damage from the attack boost of Swagger while making Foul Play more powerful. If you choose to use Sableye as your Knock Off user, Recovery is better suited as it'll keep you in the battle longer for a burn stall. Taunt and Will-O-Wisp are used to burn your opponent and cut their attack stat while preventing them from setting up either entry hazards or buffs. The Mental Herb is there to prevent yourself from being Taunt bait of other Sableye who may have invested in Speed.

Sableye @ Focus Sash

Stall w/ Adamant nature

252 Attack, 128 Defense, 128 Special Defense

Brick Break

Knock Off

Payback

Zen Headbutt

A seldom used but oddly effective set now that Sableye has been given Prankster. Since most people will be expecting a Prankster set, they'll incorrectly predict a Will-O-Wisp and switch to a Fire type or special attacker to avoid the Wisp. Once the switch happens, the new Pokemon will have its item Knocked Off upon entry, crippling certain fire type like Heatran that depend on an item. Payback will always be at base 100 power since you'll always be moving last so it provides excellent STAB. Brick Break and Zen Headbutt are then used as coverage and counters for certain common OU Pokemon, namely Aegislash and Greninja.

252 Attack Adamant Sableye Knock Off vs. Shield Forme Aegislash 252 Defense = 147-173 HP (56.3%-66.3%) 252 Attack Adamant Sableye Payback vs. Blade Forme Aegislash = 298-351 HP (114%-134%) Guaranteed 1HKO 252 Attack Adamant Sableye Brick Break vs. Greninja = 175-206 HP (61.4%-72.3%) Guaranteed 2HKO 252 Attack Adamant Sableye Knock Off vs. Heatran = 117-137 HP (36.2%-42.4%)

So while Sableye may not be a powerhouse, controlling whether you go first or last can make a large difference in a match, especially against Pokemon who rely on moving last such as Aegislash.