I've created an account not to speedrun, but to make a speedrun category. how do I do that?

Ask the moderator of the game to add certain speedrun category? Also, what game did you want to add category to?

If you are not running, what good would an extra category do?

manztellen and Oreo321, to answer your questions, I want to add a category to Yo-kai watch 2 called The Nyan Challenge (where you have to beat the game only using cat yo-kai). Yo-kai watch 2 is quite unpopular in terms of speedrunning, so I want to bring something new to the few people who do speedrun it.

Please bring this suggestion to the respective forums: https://www.speedrun.com/yo-kai_watch_2/forum

Also, it's best for you to give an example of the category by doing the runs, so that the mods can easily understand your means.

Thank you for your help Manztellen!