If joining is all what they do, it's a piece of cake.
Simply identify a pattern in their fulladdress and set a ban according to it.
In your example, you have 2 choices.
/ban *xxx*!*@*
/ban *!*xxx@*
This will freeze all bots in your channel and no other will be able to join.
And then, kick them at will.
But they do more, aren't they?
