You honestly deserve a lot more credit for building this considering how many players have stolen this team and started spamming the ladder with it; I've seen different ev spreads of the team shared around in other circles too.
Feedback after personal use of the team for a bit:
-- It's a small nitpick, but Sableye should have 4 def 4 spe instead of all 8 evs invested into physical defense, otherwise you'll have to fight through awkward speedties with other Sableye, and most importantly, ferrothorn. It's not fun switching into a power whip crit only to lose the natural speedtie the next turn and endup losing Sableye as well.
-- I'm skeptical about using sand stream on this team; If I'm using Hippo based stalls/semistalls I'm usually adamant about using sand stream to chip opposing teams, but for this team you've built here I honestly found sand stream to be more nuisance than help: some examples of this were wish-tect clef having no passive net healing through lefties, and having sableye + volcarona chipped while having to stall out a toxapex abusing the sandstorm chip against my own team and adding onto it through scald and toxic shenanigans .
`-- This one just comes down to personal taste, but something worth considering is stomping tantrum over earthquake on Hippo: it works great in tandem with SR spamming a toxiced defogger since you have an option to one time nuke with a 50% stronger earthquake on their switchin, but obviously the most notable benefit is an un grassy-terrain nerfed ground stab to punish BO mons that rely on grass terrain for safety and regeneration.
Not much else to say other than that it's a team I've enjoyed using
I've played 5793 games with this team on the alt band-aid fan(2000 elo peak) and I disagree with you on everything except speed creeping your Sableye. Stomping Tantrum is almost useless as it is very easy for anybody with a functioning brain to play around and once they do you now have a fairly shitty 70 bp move, it not being resisted by terrain doesn't matter when it comes to damaging/threatening big problems for the team like Pex. If you want a way to get kills through Grassy Terrain your best option is to go double Z-Move and give hippo groundium z so you can ohko Pex and other ground weak mons that can set up on or beat you 1v1 if not previously hit with toxic. Sandstorm is necessary to chip opposing MSab, Megas, Chansey, any nonsteel type in the game and defensive mons who you have wisped or knocked the lefties off of, without it your already fairly passive team loses any ability to pressure stall or really bulky balance teams that have a cleric and you just do nothing and die, without it the team cannot function.
An actual useful suggestion would be to change the Volcarona to this spread so that you can outspeed and revenge base 95s.