Imo, get Super Fang/Taunt/Sludge Bomb/Heat Wave on Crobat and yes, it does work as lead.
Slowking looks good although I like Bold better, but Calm will also work.
Shuckle is just gae af, but Ig if ur planning on stalling ur opponent get Toxic/Knock Off/Encore/Rest.
Steelix can have EQ/Rock Slide/Toxic/Roar. Or slide Iron Tail in there so you can handle SD Armaldo. (Maybe instead of Toxic)
If you need any sweepers, Zangoose is good af against most teams, Adamant with Return/Low Kick/Quick Attack/SD will OHKO almost anything with +2 Life Orb/Silk Scarf
Also if you need something to get rid of spikes, get a Tentacruel, you can run defensive Bold/Calm or offensive Timid, as long as it has Rapid Spin on it.