Canon Characters / Kin Galleries:+1 to banning and enforcing in all cases. If you want to RP fandom characters, you can just do that. You don't need to have them uploaded and that is all kinds of copyright/drama filled nonsense.. Kin galleries shouldn't get an exception to these rules either.
Redesigns of Canons (ex: Naruto as a Dog):+1 to banning for the most part. If it's different enough that someone who knew the show couldn't tell you that the OC was meant to a redesign or heavily inspired, then I think that should be allowed.
OCs "inspired" by Canons (ex: identical design/backstory, either both or just one):+1 to banning for the most part, but my thoughts on it are the same as the above. Backstory might be an iffy one too, since like 60-70% of all YA novels have the same backstory. The whole "cosplays as this character all the time" thing should definately not be allowed though.
Playable MCs (ex: Personal Inquisitor from DAI): I think this one really depends on how much customization the person does. If you could reasonable pass it off as an original OC, a DnD character, etc, then I don't see an issue with this for characters that are at least almost entirely created by the player. For characters like Frisk that have limited in game customization and really are characters in their own right outside of what the player makes them, I would not allow uploads follow under the redesign policy above.
OCs in Canon Settings (ex: OC Hogwarts students, OC Pokemon Trainers): -1 to banning, I would not restrict OCs in cannon settings even if they do use things like the hogwarts uniform. These really are original characters and you'd end up getting into nitpickyness about things like warriors OCs. They're.... cats in a forest. It doesn't really make sense to ban these.
OCs of a Canon Species (ex: Pokemon Gajinkas / Feral Pokemon): -1 to banning, As long as the design/backstory is unique and the artwork is not canon artwork or editted canon artwork, I don't see an issue with these. Even if this gets close to redesigns, as long as the character has a unique story and the OC's owners aren't harassing other people about a Eevee OC looking too much like another eevee OC, or two people using the same fusion type, then I think OCs of a canon species should be allowed. I think this can be seperated out from Redesigns of canon by having it very specifically be the species aspect that's important. Much like anyone can create a realistic dog character and have it be unique, anyone can create an eevee character and have it be unique.