This is just who I think would be great for Rivals.

1. N (Murder Drones), he has a good arsenal of weapons.
2. Mittens (TOH), just because there's a character in TOH in Rivals.
3. Gappy (JJBA), there's not a Gappy mod in Rivals.
4. David (Edgerunners), great timestop ability.
5. Sin (GGST), can he keep his Xrd design but keep Strive clothing?

Is this good? Feel free to actually make it, but if you don't want to, that's up to you.