It's hard for me to summarize the idea but I'll try.  

Organize tournaments or specialized leagues where only complete teams of certain qualities can participate,

for example: a tournament where only 5-star players are admitted, another where only 4-star players are admitted and so on in all categories. Rewards will vary by category, the higher the better rewards.  The winner will get a trophy depending on the category in which they are, for example, a bronze, silver, gold, diamond or platinum trophy.

As a way to finance the tournaments, a second market is suggested, where the income from the purchase or sale of juniors or players already trained goes directly to the reward fund of these specialized tournaments. 

Example: When buying a 3-star youth team, you will have an option that says Buy for a Specialized Tournament. It means that the income of that youth will go directly to the fund of those tournaments according to the quality of the youth, in this case for the fund of 3-star tournaments.

For players already trained, open an option that says Enable for Specialized Tournament, it means that the player will participate in the corresponding tournaments. however, they will have to pay a price to enable this option that will vary depending on the quality of the player. This payment will also go directly to the tournament funds.

In case of selling on the market to a player who has this option enabled, the proceeds from the sale of that player will go directly to the funds of those tournaments according to the quality of the player sold. The salaries of those players will also go to those tournaments.

Finally, in order not to affect the funds of the current competitions, players who have the option enabled will not be able to participate in normal competitions and will only be able to do so in tournaments or specialized tournaments. which means that if you want to participate in both formats and make a profit from both sides, you will have to create a second team that meets the conditions to participate in these tournaments.

To add, players will have no age restriction, which means they will be able to participate even if they are 15 years old.

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If the access to these Tournaments Is free, having the users choose which fund to feed doesn't make sense. In CL and CC, you have to obtain results to qualify.

The only feasible solution would be to send a little percentage of the youth purchases to those funds, and then automatically schedule a Tournament between the clubs with the best performance in the system Tournaments during the previous season. But I don't see a real benefit for the game in doing that 

There is no need for tournaments to feed on youth revenues generation that goes to national and global fund which are use for next season league and international competitions funding.. Already we have low prices in most league and need more means to suport the prices in those league.

Your idea of giving more allowing more options in tournaments is okay,

The funding process currently is better, organised your tournament and let those who want to participate donate as deemed suitable. 

In my own suggestions in past is that tournament should have options where I can chose how the reward system works. I seriously think it would be a good idea to host tournament where the reward is set for top 3 winner. I hope for this options where reward is given to top 2,3 or even to 5 winners. 

Current system that gives reward per win don't give some much to winners. 500 gold funded tournament could ended with a 1st position club barely making 50 to 70 gold which is just 2 platinum out of approximately 16 platinum made available for the tournament. It got splits around too much. I totally don't mind if I play in a tournament that I didn't made up to top 3 to get good reward than finishing half the table and taking portions the fund away.

If the system is made available i see tournament with huge funding and the winner gonna be happy while the rest hope for better luck in next tournament arrangements :)