I support Jellicent for the A-rank as well. It's a very very good counter for Keldeo and a nice check to Landorus-I too, which are both extreme dangerous threats nowadays. It's also the best spin blocker right now and the only viable in my opinion, Gengar loses to both Starmie and Tentacruel and it's has a bad staying power in general, Sableye loses to Starmie and it has some problem to deal with Tentacruel, especially if rain is up and it has not a very good defensive statistics though. What else? Spiritomb, Cofagrigus and Dusclops has good defensive statistics but they haven't a reliable recovery move and I don't see how they can work fine in the current metagame honestly... So yeah Jellicent is the best spin blocker in my opinion, it only loses to Tentacruel if it is running a Substitute Toxic set and to Offensive Starmie if Jellicent is not Specially Defensive or if Starmie is running an extreme offensive set with Thunder and Life Orb, which isn't really common though since many people prefer running Defensive Starmie to have a check to Rain teams (Politoed and Keldeo mainly) and to Terrakion too nowadays. Ah, of course Jellicent has Recover which is a reliable recovery move and which with its good bulk make the Jellyfish a really good spin blocker, as I already said. Jellicent can also give some problem to any Stall team with Taunt but this isn't really important imo since Stall teams aren't very common but of course give problems to Stall teams isn't not bad. The only bad thing is the weakness to Pursuit which makes Jellicent quite easily to deal with, since Tyranitar is enough to eliminate it (and if Tyranitar Pursuits the Jellyfish, Keldeo can sweep more easily later of course). However, Jellicent is definitely A-rank material.