Delcatty, Sableye and Medicham in Great League?

The only one that I have knowledge of is Medicham. It was practically built for the great league with a max CP just below 1500. Medicham is really good in great league. I've found most movesets useful.

I can confirm also that Medicham is amazing in Great league. With DP and the 2nd charge move as Ice Punch he can cover the weakness to flying types. Also, having counter as a fast move is probably the best possible for PVP. Great damage and great energy gain. Side note: Sudowoodo is also great because of counter as a fast move with the 2 bar rock charge.

Medicham is definitely a great pick for the Great League, though requires as high an IV as possible, and maxed to level 40. On my own cham I run Psycho Cut, with Dynamic Punch and Ice Punch as charge moves. It's a good one to lead with due to its wide type coverage.

Medicham with C/DP/IP is very good in great league (and especially boulder cup) but it really needs to be level 40 with good IVs. Other movesets have their merits but I'm fairly sure that's the best one overall.

Delcatty seems rather mediocre, but probably not downright terrible. It's got some relevant coverage (can hit both Azu and Altaria for SE) but its neutral TDO isn't anything to write home about.

Sableye seems ok. Fairly good moveset and only one weakness but that weakness is to a common type. Note that Sableye also needs to be maxed with good IVs.

Whenever you wonder things like these, check the DPS/TDO sheet with PvP Mode enabled and 1500 cp limit, ordered by TDO. This will give you a rough starting idea of how good the pokemon is.

Medicham is top notch from personal experience and I've heard good things about Sableye. Can't speak for Delcatty, but its moves give it a surprising range of coverage.

Medicham is well liked, and I don't know about Delcatty. As far as Sableye, it gets some good moves, but also requires large investment since it needs to be powered up quite a bit to be viable. However, it and Spiritomb may have more meta-relevant roles once Deoxys-D is out.