Don't let your memes be dreams
If LO Superpower turns out to be unsuccessful, which I doubt it will, pokemon like Chansey and Goodra will move up to GSI. Until the metagame has settled and Volcanion received an analysis I think it's best to stick with the sets posted by AM.sorry for not putting sprites in my checks list ;~;
Chansey should probably be put on gsi since I haven't seen LO Superpower volc on high ladder at all, maybe same with blissey. Kyub should be added to ssi because fire blast isn't used that much when people use volcanion and LO ep either ohkos or is a roll to ohko. tornt should be added to nsi since it can 2hko with hurri and can tank at least one hit. Latios should probably be added to nsi since Specs steam eruption is a roll to 2hko+burn chance and im psure that draco doesn't ohko volc. (mega) slowbro should be added to nsi if not ssi since it can set up on volc locked into either of its stab moves and only really fears getting hit with a hp electric or hp grass.
About your other points:
- Latios takes any hit, even Specs HP Ice after rocks, and OHKO's back in return with Draco Meteor, while it also has reliable recovery. If Hydreigon is a SSI, Latios should be too.
- I'll move Kyurem-B to SSI
- Also Mega Slowbro and Slowbro to NSI. I am not really convinced they should go SSI because Defensive Volcanion beats them and Specs 2HKO's with every move bar Fire Blast and Steam Eruption not burning.
- Still not really sure about Tornadus-T because it still has a chance to get OHKO'd after Stealth Rock damage and it has to hit 2 Hurricanes to 2HKO back. I don't think accuracy is a really strong argument but in this situation Tornadus-T is already a pretty shaky check because of the rocks weakness, so for now I won't put it on the list.
Edit: Also added MGyara. Didn't do any calcs so I'll just go for SSI for now