If I was going to be a commissioner, I'd want as few rules as possible, so I'd have to do as little enforcement as possible.
Minimum number of wins over a certain number of seasons would be a must. You can say there will be no exceptions, but the reality is world are very hard to fill and if someone seems to be putting in a reasonable effort, isn't doing anything way out of the norm ($15M ML payroll, $30M IntFAs, etc.), and falls just short, you're probably going to take him back rather than try to find someone to take the team. If you put it to world vote, they'll probably be voted another season.
I wouldn't have any rules on trades, max amount of money or otherwise. Let the veto process decide what's a fair trade or not.
If someone can win 55/120 (or whatever the minimum is) games with a $10M payroll & transfers $100M to prospects for a season or two, good for them. I can see why some worlds would want rules to limit budgets or transfers, but I wouldn't bother. IMO, that's all micro managing how people run their teams.
I would have a rule that required teams to field reasonable MinL teams at every level. No 0(0) Ps coming into games. All position players playing a reasonable position (no C at SS). Cutting back on 1 or 2 MinL levels can free up an extra $1-2M in salary. I've had many seasons where that money would have made a difference on my ML team. I'd consider that cheating the system. Rule would be something like you can't come back if any MinL team puts a 0(0) P in a game for 4 consecutive real days (not HBD days) or ever starts player out of position except for a few listed exceptions, like weak arms in RF any maybe even MikeT's C in RF. Easy enough to get 27-30 players at every MinL level, set it to auto-manage, and check once every few days to make sure you've got enough players. I've seen a lot of experience players game the system by not bothering to field 1-2 MinL teams.