Quoted By:
I believe I want more Space Jin because I fucking love ballbusting.
More seriously, yes and no. I don't think it's as strict as "waifu/bara/twink" but I do think there are certain trends and expectations. For example, it's very likely one will be defensive, one will be mixed, and one will be offensive. It's very likely one will be special focused, another will be physical focused and the third will most likely be mixed or focused on Speed. And usually their designs reflect this. Incineroar, Chesnaught and Emboar are big and buff because they're physical powerhouses. Greninja and Serperior are sly and sleek, because they're fast. And Delphox and Primarina have feminine designs that evoke magic use because they're special focused.
I don't think there's a strict pattern to go off however, since the entire Fire/Fighting saga shows they're willing to do the same thing repeatedly, but I think it's -less likely- that the physical powerhouse in Gen 8 won't be the Fire type because it was in the past two out of three gens. Considering Scorbunnys design already and following that logic, I'd assume it'll be Speed focused and will most likely have a sleek design.
