People might find an exploit or buy lots of player cards and have more of an edge in a game which is a bad recipe if money is involved. You need to have it where both team are the same or close to the same in order to keep it fair.
There is a option to do that, you can have the basic team for yourself too. In which both team won't have any kind of special player card that will give you an extra bit of advantage. And they will be trained to the max level for both of the team. And as for game control, both team will be controlled by the in-game AI and the result could be anything.
Also, having special player card will give you an advantage. Let's say if I add paid method later on, or spending your own coin which you have won on previous bets, this could be used to select spatial cards and that could increase your winning.
You can take 23 players in a game. If 11 people decides to use their point for special card, they will get X amount of extra point for winning. And if they lose they will get half the point back. For example, one player bets 10 coin for one special card. If the game is a win, he will get 12 point for that, and if he loses, then he will get back five.
I will have to do some trials and fix some errors but without practical experiments, it is hard to find them and fix them. I may do a test run in few days. I will let you know in this post and keep everyone updated.