I think all teams in which...
A and B represent the digits of the team number, and B=2A. (Or, for 3 digits, C=2B=2A, and you get it for 4 digits.) (21, 42, 63,
84, 421, 842...that's all of the teams that could exist now.)
Or any team whose number is divisble by 42
. (42,
84, 126, 168, 210, etc.)
Or, even better, if you can find anything mathematically special about your team's
number, you're in.