sage bough
One potential way to increase bot variety as well as encouraging people to not leave games that are in progress could be to "lock" a robot bay while the match it is currently in is ongoing. This would prevent you from immediately going into a new match with the same robot, but allowing you to start a new match with a different robot.
An example of a game that uses this system is MechWarrior Online, and the system generally works quite well.
stone dagger
How would this work with in-game bot switching? Is that even a planned thing? I forget...
Honestly, quite like the idea though.
sage bough
Oh right, bot switching would probably invalidate this, if it's something planned. You've got a point there.
chrome radish
could just keep the bot out of play for the entire match if in-game switching is a thing.