I made something to have teams in public Grands Prix (as teams mostly make sense in a series of races imo) - currently, there can be at most 6 teams (obviously the more teams possible, the better, but for now I sticked to emojis of corresponding colors), team standings can be shown by the same /standings command as individual standings. It looks roughly like this:
Players are highlighted in the lobby with their team color (if they belong to a team):
(The square brackets seem to be not so good-looking as for me, I'll probably remove them, they just remained from the "category" thing which I added to distinguish soccer teams in tournaments, etc.)During the race, if a player belongs to a team, the kart is painted accordingly. For now, it's better to use no fixed color (= "pick from slider") in the settings before going to a server with teams, because then you won't see your team's color on your kart and you'll see your main color (but for others your kart will have team's color, or your usual color if you have no team). However, it's probably not a big deal for a player to change that for a while (compared to recompiling a hacked version to have custom team colors in soccer, for example).
I'm not sure whether this should be present only on a GP-like server, it seems like many players like to have sometimes teams in an usual race too. (Or maybe it's just an effect of something new and unusual, lol.) For now teams are available on most Frankfurts, but you need me to set the team (as for GP you need an organizer to change teams anyway, and for other servers it originally wasn't planned ¯\_(._.)_/¯ ).