This is only my first post, so forgive me if I make some mistakes, but I want to defend Alomomola here. I'm not at all saying that this mon deserves a rise, but based on previous comments, I feel that people are underestimating it's capabilities as a wish passer.
I do not feel that Alomomola should drop.
Wish passing in general not only helps in stall, but increases the viability of slow, bulky wallbreakers. It allows these wallbreakers, such as Camerupt and even Chandelure, to make repeated switch-ins and break teams. On a more specific but important sidenote, it also makes pokemon such as Nidoking and Camerupt-Mega quite reliable checks to Koko, which is a common and threatening mon in the current meta.
I understand that it faces a lot of competition with Chansey, who is able to switch in to threatening special attackers like Tapu Koko and Ash-Greninja, which Alomomola usually cannot. Chansey's access to Natural Cure allows it not to care about status, which on the other hand, is a problem for Alomomola. However, it has a higher defense stat and access to Regenerator, and thus, is able to switch into many physical attackers, and sometimes even sweepers, to toxic stall or wish pass. Chansey, due to a low defense stat, is not able to do this. Personally, I feel that Alomomola has more opprotunities to pass wishes than Chansey does due to Regenerator. I do not think I need to go into much detail on why Clefable doesn't outclass Alomomola either. Clefable has access to Unaware, allowing it to switch into many sweepers, while Alomomola has regenerator and more natural bulk, giving it more switch-ins to wallbreakers.
Many people are saying that Toxapex outclasses this thing, which I find odd, as they preform different roles. If anything, Toxapex mostly outclasses Gastrodon, with the exception of its electric immunity. In balanced teams, Toxapex is used more as a wall, while Alomomola is a reliable pivot/softer wall with wish, which I explained the usefulness of above. I do not play stall, but I would imagine that the same differences would be present in stall builds with these two pokemon.
However, an understated niche of Alomomola, in my opinion, is Mirror Coat. This move is the main thing separating itself from the other Wish passers and defensive walls in OU. With that move and Regenerator, Alomomola can take out many threatening mons and checks, such as Blacephalon, Zapdos, and Tapu Lele, who otherwise could easily overwhelm this mon. When this move is used correctly, Alomomola can help pave way for another pokemon to come in and sweep, or act as a greater blanket check to an opposing team. Popular walls and pivots, such as Toxapex and Rotom-W, cannot do such a thing.
The other bulky water-types in B+/A- definitely have more utility coverage than Alomomola with Haze and Defog, making them, at times, more useful pivots. Along with this, they mostly have better overall defensive stats and an immunity to spikes. However, I feel that with what I've stated above, Alomomola does carve itself a decent niche as a defensive pivot, able to aid both stall and balanced teams.
E: I do recognize the growing popularity of attackers such as Bulu and Kartana, which Alomomola cannot face. Thus, I somewhat understand the want to drop this pokemon a rank or two. However, this growth doesn't necessarily decrease Alomomola's viability. Such switch ins can easily be predicted, and the mon can just wish into a counter such as Magnezone/Nidoking.