There are some real custom user groups, but those are rarer and more technical, so most wikis just use decorative ProfileTags like stated before.
Any change to groups/custom groups and their permissions has to be requested in a ticket to Fandom staff, and are normally done only if you have a good reason to do so.
Can you link the page?
According to Fandom's Terms of Use, all policies including the age requirement apply to both registered and anonymous users. While they are less likely to block anons/IP addresses, it's still possible.
From what I've heard in the past, you shouldn't use the polls feature for important decisions like that. You should require users to leave a comment with at least some reasoning. Someone probably did skew the results, which just shows the problems with the poll feature. You could also just throw away any results from users without legitimate contributions/explain the situation when you make a demotion request.
It's true that Fandom uses a different gallery extension, but it was done intentionally. These are the parameters that can be used with it, and since it's a completely separate thing from standard MW galleries their parameters aren't compatible.
Because that's just how it's set up by default. There were probably reasons when comments were first added and the functionality never changed. If you want them, you can send in a support ticket asking for them to be enabled.
You can't customize it, it only shows the most active/contributing editors
Your wiki was closed as Fandom's Community Creation Policy doesn't allow personal/chat wikis.
Since the wiki is in Japanese, you need to use this form
See this help page for a step-by-step guide
You need to upload a 1,200 × 250 px JPG file as File:Community-Page-Header.jpg as described in the help page
You should not use the CSS solution
Many wikis are automatically deleted if they're inactive and don't have enough pages to save resources. (even if they don't violate the community creation policy)
That's just what I've heard over Discord. The problem seems to only be affecting a relatively small amount of users and clearing the cookies causes something to change that fixes it for that user. I don't know if that's a permanent thing or temporary or how long until the root cause is found. Finding a solution and finding the permanent solution are two different things.
Try following these instructions to clear your cookies. Fandom is already working on a fix though.
You can use an alias like this instead of just the display text:
PageYouWantToLinkTo|TextToDisplay
See the help page for more info
From Fandom staff: if you got a 400, you should clear your cookies, it's a bug that's being tracked
You can use these instructions to clear them. It's an annoying bug, but Fandom is currently working on finding the cause and fixing it.
You 2ould have to do it client side, but it would only work some of the time (desktop with JS enabled only) and I doubt Fandom 3ould allow you to send requests to some random server for security reasons.
Periodically checking the API is unfortunately the best solution for "random" users.
You need to click on your profile and then go to the contributions tab. It's annoying but should be fixed soonish.
You can use this support form, but make sure to include links to where they admitted that they were underage as screenshots can't be used as evidence.
Sitewide or user JS is not for the same types of problems as server-side JS (node). It's generally meant to only interact with the page or other parts of the site.
If you want to send Discord messages when an article or something is created, that's when you need something server-side. Wiki-bot is does that and you can add it to your server, you could selfhost your own instance of RcGcDw, or code something server-side yourself using the MediaWiki API.