BP chains are pretty easy to stop with phazers / Haze / Taunt / powerful attacks / crits.
Gorebyss is going to be very broken. Without Slowking and Lanturn, not much can take its hits, and at +2 it's faster than all the common Scarfers. I can completely see it (and Huntail) being banned.
Mesprit... SubCM Mesprit is just so absurdly good, and it gets even better when Klinklang goes and it gets to use Ice Beam (dealing with Altaria, Zweilous, Cacturne and Torterra, its few real checks before). The problem is that there aren't really any good phazers that can take its hits, nor are there any special walls it can't set up on, and no Pursuit user actually beats it. Adamant LO Skuntank's Pursuit does 39.6% - 46.7% to max HP Mesprit, while Mesprit can do 42.2% - 49.7% back with Ice Beam / T-Bolt - an easy 2HKO after Rocks or likely after just the recoil. Absol is a similar story, except it doesn't usually carry Pursuit at all (or it's Choiced), so Mesprit can just shave off half its HP while having its Sub broken, then switch out.
I don't want to talk too much about SubCM Mesprit though, because I don't want it to get banned and I definitely don't want anyone else to use it.
Probably the mon that is going to benefit the most from the tier changes, though, is Leafeon. Magneton, Klinklang, Scolipede, Braviary and Swellow are all going, leaving it a free run at the tier. Discuss.