Here's the comment.
So I made a guide awhile back of just basic rain roles that I'm not going to particularly link cause it's outdated in the sense that some of the stuff usable are pretty niche and or don't work that well in the current meta (like Chesnaught). This leads to my next points. I'll try to go in order of the OP.
Good Cores: Offensive, Defensive, Balanced
Your cores are pretty basic but it seems like you just plopped stuff just to plop stuff in like M-Hera / Bisharp which I guess is ok but their synergy isn't a thing only to rain. I'm really not a fan of the M-Sableye / Toxicroak core from using it in the past :/ (sorry SketchUp) I think it has a ton of problems that its effective in theory yet keels over to the reality of what they're trying to cover. Toxicroak is barely a check to fairies and in order for Toxicroak to beat most fairies in the tier, it needs a free switch in. Free switch ins are extremely rare for Toxicroak outside of ballsy predictions or calculated doubles.
bludz has been using a Poli / Celebi core everytime he brings in rain in matches I have with him and their synergy I think is really nice considering Celebi supplements a TON of stuff on his team through either Baton Passing for momentum purposes or just passing over a boost to something like Torn-T. I guess this might be a balanced core now that I think about it but meh. The other defensive cores not too concerned with I never saw the point of using a rain stall team in ORAS, maybe I'll try it out sometime in the future for shits and giggles.
M-Manectric / Torn-T is fine I've used that a good amount. The Moltres / Rotom-W duo being "odd" is an understatement lol. I think Moltres is actually pointless in rain and is much more effective in sand with a SubRoost dual STAB life orb set. Running a Moltres on rain just makes your team weaker to the likes of Azumarill and Keldeo which is seriously the last thing you need for two things that are already mindless to begin with in some battles.
I've been sort of busy multi-tasking different things, shitposting in Skype, watching Avarice be his weird self in the OU room, and writing long explanations like these so when I have time I can provide some rain sets and what not in that section you're missing.
Rain Setters: Rain Setters, Swift Swimmers, Other Sweepers
I'm not a big fan of the rain setters you're implying here. For example most of the rain setters rely on some sort of defensive utility which leads me to believe Meowstic is a pretty poor choice to the much more superior Uxie and Azelf. I'm not thrilled by using Rotom-W on a rain build simply for the fact you're not really adding on any sort of beneficial role compression or real utility other than what Rotom-W does by itself. It's a difference with stuff like Thundurus because it has the option of running variants to break down normal checks to rain such as M-Venusaue with HP Flying while offsetting offense with Thunder Wave who normally annoy conventional rain builds. I think you need to put emphasis on the rain setter thing in terms of everything outside of Politoed is a luxury, and a pretty large emphasis at that. Most rain builds only need Politoed, secondary setters are actually quite rare considering that the majority of them are either niche or in the case of something like Latis want to be running coverage or other utility to help the team. I've only seen 1 good build use a secondary setter in ORAS and that was doughboys rain build early on in ORAS with M-Swamp, Thundurus, Kingdra, Politoed, Klefki, Breloom. Every other rain build I've seen that is effectively used only does so by using Politoed.
I'd go as far to say that if you're gonna place stuff in the way you're doing by Tiers through Stars
Kabutops is most certainly not a 3 Star Swift Swimmer. I'll take the ballsy route and say that Kingdra should be the only 3 star Swift Swimmer on that list considering there's about 3 good switchs in to it tops with Ferrothorn, Chansey, and Blissey. All the other Swift Swimmers on that list have either pretty apparent flaws or wiggle room to play around them more effectively, whether it be through their own implementation of teams through synergy or individual effectiveness. Ludicolo is really like a 1 and Beartic would be like a .5 lol. If I really wanted to troll somebody I would just use specs tyranitar or some nonsense that I usually troll people with effectively.
I think M-Scizor is overrated so no comment I'll take that 3 star position with a grain of salt for the time being. There's so much better to use than M-Bro on rain I don't see the point of actually having it there what so ever. Reuniclus seems like it was just thrown in their for more laughs I don't really quite get its specific trait for rain that it would provide other than naturally checking stuff like M-Venusaur which it already does without rain anyways. SR M-Swampert is a huge liability considering it's always gonna need that 4th move to break certain archetypes.
Rain Type Viability Rankings:
Not liking the idea of this one and some of these are extremely subjective but I guess I'll bite. Some of your stuff also contradicts some of the prior things you mentioned like Garchomp being a Tier 3 Hazard setter (which it is) but not even in the top of the rankings. Toxicroak really isn't a top level rain thing it's more mid. In the future I think a pretty large clean up is in order seeing as some of these are either too much of an opportunity cost or plain bad. The whole "unviable" argument people use I sort of have slowly calmed down on contrary to this forums tendency of screaming bloody murder about that but it's silly to see some of these on there since you would never realistically use them even to mess around (like Meowstic).
Rains pretty easy to build lol so again when free I'll throw together some teams and sets.
Fyi, Topics of the week suck. They always have just from seeing other threads try to dedicate topics when stuff like this it's better to just have a general place for discussion to include replays, teams, sets, relevant points, etc. that's it for me for now might come back later.