A team needs to have 5 good players and other 5 players of a lower level as substitutes. 18 players as max numbers is too much and this will not limited at all the trading. I can earn 200k from a sale of only 1 player, so I think we should limit the profits not the players. Of course this can help when there are people that make profits trading a lot of players but if you want to make trading also one player can give you a lot of money.
1990-2022 Stalinorgel - https://www.youtube.com/watch?v=pV-Xppl6h8Et