Hi, yes every bot does play every other bot atleast once (could be more than once)
Essentially every match has 4 bots playing against eachother, and the bots are assigned matches to play using a round robin matchup to get an overall bot average score.
So some games your bot might come first, others it could come last, but overall how are you doing against all others will determine where you end up on the leaderboard. This ensures every bot has a fair fighting chance.
There are a lot of runs of the game (the figure varies on the number of participants ) but always follows a round robin style of play (even till finals)