Skitty is bottom, agreed. Buneary, idk. Karrablast is fragile, meh coverage, mediocre speed, so agree with bottom. Shelmet can go without saying that it is bottom tier—really slow, crappy offences, average defences complimented by mediocre HP, & a very defensive orientated move-pool. Clefairy it has an amazing movepool, instant evolution, & decent Sp. Attack & bulk, but the timing which you get it means that low seems quite fair to me.
Vullaby? Pretty clear bottom tier to me. Rufflet is a decent end-game attacker who can be quite handy against Marshal, & possibly Caitilin & Grimsley to warrant using it, so Low is pretty fair, especially given you get Braviary on Route 4.
In general, I agree with the proposed placements. Also TM13, Rufflet can only be obtained on Route 23, iirc, so no Rufflet before Marlon... :/