Cool idea with the Knock Off Zam, will give it a shot.
Why do you have such a big gap between the viability of Bulu and Tang? They both work as great water resists and especially as great pivots into Ash Gren (which even you acknowledge is one of the best mons in the meta currently). Bulu does provide a greater offensive presence and the possibility of offensive sets, but I would argue Tang has its own advantages in that it can check Mag with EQ, check opposing Bulu with Sludge Bomb (as well as provide poison support with that 30% chance), provide Knock Off support, and has regenerator so it doesn't need to run Protect/Synthesis like Bulu. I get that Bulu can catch things off guard with an offensive set, but then it becomes a much shakier check to stuff like Ash Gren and rain.
Also, I disagree with the relatively low placements of Lando-T and Rotom-W. While I get that they're not big sweepers, big breakers (except the rare offensive Z Lando), or walls that can stall things out indefinitely, they still act as great pivots that can come in on big threats and U-Turn/Volt Switch out to get your threats in. They can also both use Defog if needed and can act as great role compression in general. I guess I'm just confused on why you seem to be underrating pivots on your tier list in favour of big breakers/sweepers. I'd like to hear your thoughts on this, as I think pivots are invaluable in being able to actually get your big threats in and keep your opponent's team in check defensively.