Yo, I'm subbing Grass/Fighting.
Commentary on types that I'm iffy on:
Gonna answer this one first. The most glaring aspect of this typing is its deathly fear of Flying-types, but I think being able to lure in Flying-types and hit them with either neutral STABs or a SE Diamond Storm has quite a bit of merit. Looking at some relevant Flying-type switch-ins:How does this type complement Diamond Storm coverage-wise? If this type does not have STAB on Diamond Storm, how does it justify using the move and how much value does the extra STAB coverage provide?
Ground is the most notable resistance here, meaning being on the receiving end of an Earthquake is a lot more breathable, especially with a +2 Defense boost. Grass/Fighting also resists Dark (aka Knock Off), which can come in handy. Some less useful, but still notable resists are Electric and Water. Resisting Electric can make it easier to deal with Zeraora in tandem with a Knock resist, though Close Combat could potentially still hurt. A Water resistance sounds nice, but Scald burns are no bueno, so leveraging this resist is dicier. Taking less damage from Rocks is also quite helpful.What useful type resistances/immunities does this type have that mesh well with Diamond Storm?
Does this type come with any additional benefits that are particularly appreciated by CAP 31? (ex. Stealth Rock resistance, immunity to a status, etc.)
What comes to mind is Ice, aka Weavile. The Knock resist helps a lot in this MU, and this typing can potentially tank through Weav's Ice attacks to KO with Fighting STAB or Diamond Storm. Fire in the form of Astrolotl is also kinda notable since +2 Defense can mitigate Fire Lash's Defense drops, though Scarf Astro can potentially hit hard with Draco anyway. Unfortunately, every other type that Grass/Fighting is weak to is either the 4x Flying or is mostly only relevant on the special side.What weaknesses does this type have that can be effectively patched by a Diamond Storm Defense raise?
While I did point out this typing's defensive capabilities, it is definitely more of an offensive typing. Grass/Fighting is straddled with a ton of common weaknesses. Grass/Fighting's main strength is the powerful coverage offered by its STABs combined with DStorm. Grass/Fighting can potentially use its resists to find switch-in opportunities and make it more difficult to KO after a +2, but its easily exploitable weaknesses means it would much rather lean more on the offensive.Does this type seek to use Diamond Storm offensively or defensively? Or does it leave this more up in the air?
Commentary on types that I'm iffy on:
Cool type, but why would this run Diamond Storm? Electric/Dark offers excellent neutral coverage that makes Rock completely redundant. The only relevant mons that resist both types are Tapu Koko, Jumbao, and Colossoil, none of which are weak to Rock and the latter resists it. Astro is listed as something Diamond Storm hits, but if this type is getting Diamond Storm, it's gonna lean physical and very likely be given Knock Off, something Astro is not gonna like taking anyway. If anything, this type would probably run DStorm to hit Zapdos, and that's pretty much it. I don't see why Electric/Dark would run DStorm outside of that.Submitting Electric/Dark
This one is sorta hampered by having a deceptively mediocre defensive profile and awkward coverage. Neutrality to Flying in tandem with weaknesses to Fire, Fighting, and Ground means it's more easily pressured than other Steel types in OU/CAP, which either resist Flying and/or aren't weak to one or two of Fire, Fighting, or Ground. Steel/Fighting also gets hard-walled by the Slow twins, and really only wants Rock coverage to prevent being hard-walled by Zapdos and I guess to hit Venomicon-P harder. This typing just doesn't use DStorm as well as other typings I feel.Submitting Fighting/Steel
My thoughts on this are similar to Electric/Dark, in that it's gonna be using Electric STAB more than it's gonna be using Diamond Storm. Except Bug/Electric isn't as strong as Electric/Dark. Bug resists are way more common than Dark, making it a lot more exploitable and Rock coverage doesn't really fix that. It also can't put its resists to good use, since it does not threaten any of the types it resists with SE damage (not even Grass since all of the prevalent Grass-types are neutral to Bug). Not to mention its vulnerability to all hazards means it's married to Boots. I guess it does have some incentive to run DStorm so it isn't hard-walled by Astro and Zapdos, but this is another type that doesn't really take DStorm to its full potential imo.I propose Bug/Electric.