Is there an effective stall team to use atm after the tier shifts?
It's not a very standard stall team for several reasons, but it still is unquestionably full stall and follows the most important rules of stall, namely countering the metagame and providing utility moves.
Double Wish is useful because Klefki has pretty bad bulk for a wall and no Recovery, although you could make Umbreon Moonlight to get more utility moves in like Taunt/Sucker Punch/Toxic. Still, Protect is great for beating up Volt-Turn that relies on Choice Infernape and Scizor to beat Umbreon.
Klefki's set makes it a defensive threat as it wals some stallbreakers like NP Togekiss, CM Latias (to some extent), Gardevoir Mega, and Work Up Pidgeot. Spikes doesn't ever hurt, although you could always change it since the team doesn't abuse Spikes that proficiently (no blocker or shuffler).
Umbreon is uncommon but viable, Inner Focus is mainly for Sharpedo and Mamoswine and Weavile. It also helps counter Haxorus which is pretty hard to do, even if it is not a perfect counter.
Tentacruel has Icium Z although that could be Black Sludge, Icium Z does help a tad with Crawdaunt though and the surprise recovery is always nice.
Everything else is pretty standard for stall, ultimately the team does not have many weaknesses apart from hazard stack +Ghost, Crawdaunt, Haxorus and Heracross.