Firstly, what browser are you using? My answer is different depending on the browser.
If you're using the visual editor (Chrome) and you can't find it in the infobox inserts, then go to the templates section. It's titled "Infobox Character."
If you're using the classic/source editor (Internet Explorer), then you will have to go to other pages and copy, paste, and edit the infobox into your editor and it should appear.
I've added the template:Infobox Character to your page. To learn how to use templates, go to the search bar and type in "Template" then a colon and the name of the template. The character one would be "Template:Infobox Character."
Okay. I've looked through the edit history of the Emma Agreste page, the Royal Flush page, Dragonflymiraculous2006's user contributions, and a couple other little things. From what I can tell, they were only trying to be helpful while inserting their own headcanons into the Emma Agreste page.
Technically, any user can edit any page on a wikia (except for a handful that you have to have admin privileges for). There is no way that I can protect your page from being edited by someone who is not you. The note that you wrote at the top of the Emma Agreste page should be sufficient to prevent it from happening in the future.
As for the Royal Flush page, I know you didn't bring it up here, but I do believe that Dragonflymiraculous2006 was just trying to be helpful again and add in their own headcanons at the same time. You're free to edit that page to fit the series you're writing.
If the editing happens multiple times in the future, please bring it up with me again.
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We on the main wikia are going to help this wikia with its colors and everything. Because of the hiatus and Papapillon wanting this, it's going to become a top priority. We just have to discuss everything first and figure out how to switch the colors and everything over here so that it all matches.
Discussing things is good. Don't forget there is still a founder here and it's polite not to step on his toes and make him feel like you are taking over the wiki :)
It's great that you want to help though, and jazzing up the wiki is a great way to start (if the founder is willing).
The Founder can help you with switching colours, either by copying over what you suggest or by making one of you an admin. But he may not be ready to do that. It's possible that he might want people to contribute article to the wiki before he promotes.
So, I'm looking at the tabs underneath "Popular Pages." One of those should be changed to Akumasona and the other should be changed to Miracusona, that way, pages with the category of Akumasona or Miracusona will appear there.
I'm looking through the pages, and there are OC Kwami that show up too, so if there is a tab for Kwami, then the pages under the Kwami category could show up there. It could be a dropdown from Miracusona.