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There is some team play element in worms (not much, though) so 2v2 rating could indicate your team play ability
But you are right, individual 2v2 (or team game) rating doesn't make much sense. It's just for some fools who think they have achieved something when they get a high rating.
We could have 1v1 playoffs at the end of the season to see who really is the best. To qualify to the playoffs, you would just have to play 2v2 games instead of 1v1. Does it make any sense?
Or we could stay in the current system of TUS singles league with 2v2 possibility. We just don't see many 2v2 games because
1. Success is dependent on your partner also and most people are not willing to risk their singles rating playing 2v2
2. Having two pairs of friends looking for a 2v2 match is a rare situation. Having 4 random players coming to an agreement of a 2v2 match is just impossible.
Your idea of IRC bot with some added rules could solve the problem 2. It wouldn't require much work from MonkeyIsland either. We should just get logs from the bot as evidence of the match. Otherwise we may end up having 3 players lying one player (who they hate) didn't agree to play. With Tomi's Great Snooper and its TUS login feature we could prevent people from stealing others' identity.