This topic has been brought up so many times and the answer is the same every time. No. I understand your pain, I've been playing MCSG for 31 months, and I've encountered every type of team, hacker, and glitch there could possibly be. You just have to move on. Teaming, although annoying, is a part of the game.
So what if we created solo servers only? They'd have to have a separate leaderboard, so you'd have to start over on your stats, it would be almost impossible to actually create. Even if you put say invis pots on people, you can still identify teammates by armor, etc. Plus people would break this rule very often and would only lead to more complaints about how the staff apparently can't do their job regulating it.
It's much harder than it seems. These solo servers would probably die out quickly anyway.
Seeing as we have rejected this before and will continue to have the same result I will lock this thread. Sorry for being the bearer of bad news :c