octillery with choice specs is pretty awesome. it learns a great variety of attacks: surf, ice beam, flamethrower and energy ball. it may be slow, but if you max out its sp atk and hp, it can take hits and shoot even stronger ones back.
slowking has nasty plot and has a decent variety of attacks.
nidoking has an awesome variety of attacks: earth power, ice beam, thunderbolt, flamethrower, sludge bomb, focus blast and dragon pulse. paired with choice specs or life orb, it can do some serious damage.
mismagius has a decent movepool as well. it can be utilized in various ways.
houndoom has nasty plot and though it has a very limited movepool, STAB dark pulse and flamethrower cover most, if not all, threats.
magmortar is a very fun special sweeper to use.
manectric isn't so much a "sweeper" but it has a decent special attack stat, good speed, and has both thunderbolt and flamethrower.
ninetales also has nasty plot, and with flamethrower, energy ball, and extrasensory, it can manage.
lunatone has a decent sp attack stat, and a very forgiving movepool. it has calm mind, hypnosis, ice beam, psychic, charge beam, grass knot, explosion, rock polish, and reflect/light screen. you can just about adjust this poke to do vaerieties of things for your team.
sceptile makes for a good sp sweeper.
ampharos has a limited movepool, but it can manage if given the right moveset.
lickilicky with choice specs is a novelty that i like. it has a very good movepool and a manageable special attack stat.