[quote=@Nib]
<Snipped quote by Inkarnate>

I'm actually putting him on an X-Men team. I was trying to find other DC characters who would fit with the X-Men, specifically from the Doom Patrol.
[/quote]
If you're changing Beast Boy into a mutant then virtually any Teen Titan could possibly work. Though you might wanna stay away from the more popular characters (Starfire, for example) because chances sooner or later other person may come along and apply for them.

Here's a [url=https://comicvine.gamespot.com/profile/holly_cross/lists/dc-teens/45605/]list[/url] that could give you some inspiration.