These anti-rank posts make me want to rank it lol, so ill respond to some of them (tbh megazard, hilarius's post isnt really cherrypicking rather your response just seems ignorant)
Palpitoad has a niche as well. It walls both Smashers, sets up SR and also walls a multitude of Pokémon in the meta (rapdidash, Klang etc). Has fantastic utility in Water Immunity + Electric Immunity and only one weakness to Grass. Palpitoad has a niche.
Palpitoad is also E Rank.
The reality of the matter is, despite its obvious utility and "niche" its not actually "good". And by good, I mean on par with mons in D Rank which have recognises niches. The set you showed us obviously gives wailord a niche, and I commend you for finding a niche for that otherwise useless Pokémon but in reality; where is it ever going to work? It's a cool set around pp stall, but outside of stall, it looks useless and pp stalling for the sake of it, not to mention settup fodder for loads of mons.
The significant amount of team support, rarity of opportunity for this to actually work and how bad the playstyle for this to actually work is in meta right now warrant E Rank imo.
The part about palpitoad is irrelevant (though you wouldn't know that when you posted), as (i'm p sure) we (the VR team) were going to rank palpitoad, well at least I know that we acknowledged it is d-rank material in this current metagame. A big point of wailord is removing some of the more troubling set up sweepers for stall/other very defensive teams (like clef/duo), and outside of that, it can actually stall out a lot of pokes with toxic spikes (you can pp stall flying/levitators - the main issue with this strat tho is other rose/arbok but although it is matchup reliant, that isn't enough to keep it e-rank). You can actually pp stall most set up sweepers lol
The main reason to why this wouldn't be ranked is to do with matchup reliance (team support isnt even that much and stall's viability itself wouldnt keep out of d), and since it can effectively remove specific threats, possibly weaken the opp with toxic spikes, and even be a check to some pokemon means that it is enough for d-rank imo.
About the Wailord issue... I've got to add a few things...
1.- Your set needs Toxic Spikes, which makes you almost for sure run Roselia... Ok, Roselia is a nice pokemon but if you are trying to use Toxic Spikes then you are probably running a defensive-stallish set, right? That will make a third of your team terribly passive in a tier where NP Simis, DD Fraxure and even things like BU Floatzel (I'm not saying its good just bringing it as example) or QD Butterfree can bring down a team after a few boosts... And of course, I'm not even mentioning the Smashers...
2.- You know that a lot of those things that I've mentioned in point 1, also have Taunt (And Butterfree just bypass subs with Bug Buzz)? Which will just make you deal pitiful damage with a non invested Scald (for God's sake, it can't even OHKO Simisear with a freaking STAB supereffective attack, which also means that it can't break another subs like Simipour's and Simisage's) and stop getting subs and protect...
3.- While your Rose sets Toxic Spikes, another Setup Sweeper can just... You know... Setup themselves... Or do you think that you will have 3, 4 or heck even 5 free turns? (One or two turns of Toxic Spikes, one to switch your Wailord that can be skipped if you sack your Rose, one for Aqua Ring and one for a Sub)
4.- You know that Wailord has 157 speed with 4evs? I think that a lot of things can outspeed that much speed and then beat the crap out of Wailord before it manages to get the sub, even if you can get the Aqua Ring on the switch (and if you get the sub, it will get broken when you try to setup Aqua Ring)...
5.- Infiltrator, Bug Buzz, Encore, Trick, Hyper Voice, Knock Off, Status Phazing, Any Status before you got the sub, Hippopotas Sand Stream, and of course Taunt just deals with that "Stallord"... That's a kinda big list for something that has a niche, especially when we consider that Knock Off, Taunt and Phazing are really common in this metagame...
6.- You know that Magic Guard Clefairy can also play mind games and get Calm Minds and do a lot of other shit like spending turns setting SR again and again, Recovering easily the damage at +6 and then PP Stall Wailord attacks? (SR has 32 pp that means 16 uses because of Pressure, Calm Mind also has 32 PP that are 32 uses because the move do not affect the enemy... Those are more than enough to deal with 24 PPs from Scald and even to make it burn a few PPs from Substitute, Aqua Ring, and Protect)
0 SpA Wailord Scald vs. +1 252 HP / 4 SpD Eviolite Clefairy: 51-60 (14.8 - 17.4%) -- possible 6HKO
0 SpA Wailord Scald vs. +6 252 HP / 4 SpD Eviolite Clefairy: 19-24 (5.5 - 6.9%) -- possibly the worst move ever
7.- I would rather lead with a Scarf Wailord with Water Spout and spam that thing for a while, since at least can outspeed a few things and even has a decent chance for the 2HKO against the simis and a OHKO against uninvested Costa (Smash Costa)... And sadly that's not enough for a niche on PU IMO...
I really like low tiered Pokemon but that Wailor Set is just a Gimmick... Can be annoying and make a few people forfeit on frustration but nothing else...
Those are my two cents... See ya guys!
Edit: sorry... I've got greninja'd on a few things xD
1. Stall is built with passive mons but still is viable (roselia isnt exactly a passivemon tho), and they have ways to stop all those set up sweepers (for example piloswine/misdreavus can beat fraxure). You listing butterfree and the non-existant offensive BU floatzel as threats to stall show that you don't really understand how these teams work
2. Taunt really isn't very common in this metagame. Yes simipour or w/e can run it, but it would much rather have more coverage (like low kick to not be countered by lickilicky). Butterfree is one example, which is not only uncommon (for a reason) but it also is stopped by lickilicky/other special walls, you are not staying in vs a butterfree to try and PP stall when you know they can beat you one on one
3. I don't think you understand how this works
4. Wailord has surprisingly good bulk, and you aren't setting up on raichu or zebstrika, rather passive mons like clefairy, or mons you force out like piloswine. If you aqua ring on the switch (or sub on the status), and if they switch to something that cant do over 75% (you can protect before to heal off hazard or chip damage, then you can sub down and stall.
252+ Atk Life Orb Carracosta Stone Edge vs. 0 HP / 252 Def Wailord: 255-302 (53 - 62.7%) -- guaranteed 2HKO
5. A lot of these are stopped by sub, bug buzz is irrelevant (nothing outside c rank uses it lol), encore is rare (only used by kadabra, which doesn't always use it), infiltrator is limited to one relevant mon, which is the biggest threat to wailord but hates burns, hyper voice persian?, you aren't setting up on faster status users, hippo's sand is rare af and doesn't last long enough to be detrimental, grumpig is the only phaser that goes through the sub and they mostly use offensive sets, and like I said earlier, taunt isn't common (only missy and pig will use it on their standard set and they dislike burns).
6. Im 98% sure calm mind uses 2 PP, and you PP stall till it struggles
7. Simipour z_z
Overall the best ways to prevent this set from 'setting up' is by a few niche moves/mons, or by immediately switching out into a poke that does over 75%, which isn't exactly a natural thing to do vs a wailord even if the opp is running stall. Honestly typing that prior sentence has made be less sure about whether it should be ranked, though these posts have shown me that people don't understand the strat, and need to focus more on the 'over 75%' part of my post.