MIND CONTROL CLOSE/RANGE: Minimum range value 4. Make a close/range attack.
Instead of normal damage, a hit character halves speed and becomes friendly to your force and may in either order: Move and/or make an attack. Then it reverts forces.

If I mind control all of my opponent's remaining characters, do I win the game since he no longer has any friendly characters on the map?

No.

No, that is no longer a winning condition. It's only when the whole force has been KO'd... but even under the old rules, it was after the action had resolved for that very reason.

Ok. Thanks. It came up in a game recently and I wasn't sure. I thought it used to be a thing but was unclear and couldn't give a definite answer.

This isn't exactly right. You don't need to KO the whole force, and it currently is after the action has resolved. So, right conclusion, that mind controlling all the remaining opponent's characters doesn't end the game, but the reason is that mind control has to resolve first, not that they all have to be KO'd.

This might matter with the rare character who can take a character from your opponent's force and keep them after actions resolve. Like the old Jericho.

If Mind Controlling an entire team were a win condition, the game would be far too easy, lol.

True enough, they recently added that "100 points over" stipulation because of those darned Ultron drones and lucky rolls on certain hydra teams (neither of which really saw competitive impacts.