I created a team with some friends of mine a while ago (Team Megan Bonnett, you may have heard of it) and it started out pretty well. It was intended to be pretty laid-back, focused on community rather than competition, and while that succeeded to a certain extent the lack of strict moderation meant that it just devolved into a toxic mess.
Some of the more serious players tried to revive it in a new server (Team Trump Card) and that was going great. Unfortunately, COVID happened, and tourneys stopped being a thing; this meant that the serious players stopped really talking, and the only people who were were the people from the previous server that just didn't care. And so the same thing happened.
Perhaps some time in the future I'll try to restart it again but I don't think that'll be happening for a while. The best advice I can give you is to not let your team fall into that trap: have a clear idea of what you want your team to be about, and try not to deviate from that.
That being said, good luck, and I hope it works out!