@Emma Of The Sea Do you know if this can work?

Unless it's an auto created template from Fandom (Series, Book, Film, etc), then no, I don't think so. I could help you with the template if you tell me what it is.

I guess you could import the template code into MediaWiki through @import and create a div class with it maybe. Idk if that only effects CSS and not JS or HTML tho.

Oh, ok. I want to make custom templates for a wiki, but they won't let me since it can't really be used on actual pages. Maybe you can test it real quick and report back.

If the wiki just doesn't want it on their template namespace, you can always just have the template be in your user namespace and use it from there. Basically instead of having the code in a page called "Template:ABC" you can put it in a page called "User:NAME/ABC" and then use it with "{{User:NAME/ABC}}" with your username where NAME is.

Ohhhh ok

As for the original question - no, it's not possible to use a template from another wiki without copying it over. The only exception is templates on Community Central which can be used on any other Fandom wiki, but it's only recommended for specific usecases that require a global template.

Ok