I need help randomizing my teams! Can anyone help make the teams randomized and even?

I am making a game and after a round ends I want to randomize the teams, I have a set up right now but it makes the teams uneven and I REALLY don't want that! can anyone help to

1. Randomize the teams using only code

2. Make the teams even so that one team had 6 people and the other only has 4

3. Can run this code when ever needed