There's a presiding team value function that impacts and steers team play. The bots 'communicate' through this. There's nothing magical going on.

As a counter bot strategy, I'd work on how to break and trick it using multiple-stepped logic that an optimization function would be unable to see beyond. I'd also use varying tactics of chaotic/sporadic configurations. The bot isn't 'playing fair' nor should a human w/ intelligence. The advantage being that a human can think along a multitude of strategies and adapt. The bot is only optimizing some steps ahead.

Their 1v1 bot was defeated in this manner and it just goes to show what true intellect and superiority is. I've played random pub games w/ little to no communication and have had all other 4 players converge on different strategies based on a perception of what's going on. If someone decided to cheese/snowball, you simply wait it out and let them push themselves into a nightmare. I saw little to none of this in the games I watched which leads me to question the intelligence of said 'pros'.

The team value function is just a hyperparameter that describes how greedy the individual agents are. At the start of training the team spirit is 0 and the bots are only rewarded for their own actions. This encourages them to learn basic micro skills, like last hitting. As training progresses the team spirit is increased. When it finally reaches 1, the bots value a reward for a teammate as highly as a reward for themselves.

The actual source of the "communication" is not the team spirit parameter, but the basic fact that the bots have been trained together and they receive the same inputs when making decisions. Unlike humans, who have a limited focus to their attention, the bots can look at the whole map at once. They don't need to communicate because the already "know" what their allies will do when given the same input.