I do have some thoughts on SDPass.
I am not familiar with the mon (i say the mon, you will understand in this post later) but I do think SDPass Cele always feels underwhelming for a number of factors, and I want to discuss that, as I feel this one variant of Celebi is its most underexplored, alongside sets like SubCM (which to be fair, isnt really explored due to the fact it struggles at beating offense, which btw is the same issue I have with CM/Seed/Psy/Giga, which I consider a not so great set nowadays due to also struggling vs opposing offense).
Pass Cele is one of the most unique pivots of the tier, it can swing momentum insanely hard depending on the MU but it can also fall off drastically depending on said MU too, I like to think of Pass Cele as more of a Spikeless mon, as said teams with "6 strong mons" or Magneton Offense or even Dugtrio Offense usually like the idea and offensive benefit Boost or SubPass provides, SD is unique as it is the one most likely to close out a game, but its also the one that fails the most consistently, ideally, the most consistent Pass set is SubSeedPass, however said set has great problems of fitting into teams and is overall difficult to get consistent teams and use off it, CMPass for this reason is by far the most splashable, as special or mixed attackers r extremely dangerous in ADV and the boost complements them perfectly, however CMPass still has the same old Zard/Aero/Molt/Mence/RoarZap problems, which sucks, not to mention the 2 move coverage problem (which is a reason I dislike SD/BP + 2 attacks) that makes life hell, especially since no matter the combo, you will be walled by something relevant. However SD/Seed/Recover/BP is a interesting mon, Seed+Recover earlygame can be a lethal bluff for a SDPass lategame, which can be unexpected, however this "unexpectedness" unfortunately falls flat once u realize that most people do in fact use Mag there, making it a very linear and easy to deduce strategy, not to mention that while the longevity helps, it doesnt fix the whole RoarZap/Aero/Zard/Molt problem, it is however the greatest punish to a bad CB lock or gives a nasty surprise by the bluff. My next idea is probably to try and use SD/Seed/Recover/BP alongside mons that hit Skarm extremely hard (think Max Spa Pert, +1 Dedge Lax, maybe CB or MixMeta) and use SDPass to finish off opps by passing off a surprise SD to a threat, perhaps Agility Meta in this scenario, that makes SDPass much more inherently dangerous, as Cele can easily run anything in these "6 strong mons" types of teams, making it a near ultimate versatility tool, jam up Skarm earlygame as the opponent is unsuspecting and reveal Celebi mid to lategame to reveal a nasty SD, or just use Celebi early mid game and spam Leech Seed+Recover+BP, only to reveal surprise 4th SD endgame, obviously would need a lot of Skarm lures ideally like Max Spa Pert, Curse Dedge Snorlax, Band/DD Ttar, maybe Band/Mix Meta, but all in all, its a interesting concept which I have seen before but not seen it been give as much thought as it deserves, perhaps it could be more explored or anything of the likes.
Sad fact I cannot run SD/CM/Seed/BP as a set. That set really appealed to me when I was a noob, I wish I had made it work. It will never be forgotten.