After a long stint at the top of the leaderboard, Ferrothorn has started to decline in usage but is hardly less effective. With access to Spikes, SR, and Leech seed (but not all at once, sadly) he can support his team well and heal himself fairly well to boot. A crippling 4x weakness to Fire hurts, though.
Jirachi has two main purposes in life: Iron Head Flinch and a great mixed wall. With Steel typing allowing it to tank Draco Meteors like a boss and the ability to hit physical or special makes him a force to be reckoned with.
Cresselia, for instance is something I like to use every now and then because she's the best counter to DD Multiscale dragonite. She also counters all types of terrakion (X-scissor doesn't 2hko), landorus, haxorus, and a multitude of offensive Pokemon in general. Sure, she doesn't phaze or put up any hazards. She can't wishpass either. But she avoids becoming what other defensive walls usually end up being (a complete momentum killer for you, not your opponent) by being scared of very little. By running hp fire on my (what else?) sun team, cresselia is able to lure in the Scizor part of the Scizor/Rotom duo and pick him off without any prediction. She also countered excadrill, and when blaziken was around she took care of him too (mixken lost, and drought was absolutely necessary for SD AdamantKen to stand any chance).
One word: Unaware. Quagsire is able to stall out all boosters with his gift of an ability. Recover, Stockpile, Curse, blahblahblah.