Building a bracket

New user, long time developer. I feel like I have an ok grasp with bubble. Super easy to use and a wonderful UX. 10/10 would recommend.

Here’s my problem. I can’t think outside of the box. I want to build a bracket system for mma that randomly pits two fighters together with the same attributes I.e. Weight group. Another part of that problem is the number of fighters isn’t fixed.

Any starting point suggestions?