Pre-match arrangements

In the last match, a guy told me that he didn't want to win, and he only entered the game to boost his friends. I told him it was against the rules and he said he didn't care. Is there anything enforcing the rules? Or is not a rule, just a guideline?
In the current match, I suspect the same. One guy isn't playing, didn't mine, and it's just gifting away his subs to other two players, who of course are allied and always attack the same target, at the same time.
NO PRE-FORMED ALLIANCES: Players may not come into a game with the intent of playing together as a team.
In the current match, I suspect the same. One guy isn't playing, didn't mine, and it's just gifting away his subs to other two players, who of course are allied and always attack the same target, at the same time.