teams?

how would i make a datapack make teams, i am making a datapack for a server that when you choose a team, you get a potion effect based on that team. i just dont know how to make the datapack make teams. could i just put it into a load.mcfuction? how would i stop it from making teams when ever the server is reloaded? is there a way i could make it a 1 off thing that only runs the command once