The question is not about entertainment - the question is that some martial arts contain punches to the face, which is forbidden in Islam, even to the non-believers captured in war - without extreme need for this - not to mention the entertainment between each other, not to mention already about involving children in this
First, Islam prohibits hitting the face and, in general, somehow mutilating the face in any way (deliberately mutilating the face of the enemy is prohibited even during a war with infidels). Secondly, Islam prohibits any violence, except during war, for educational purposes (but here violence is strongly limited and should not cause real harm to health), as well as in order to protect your life / property / privacy. Thirdly, Islam prohibits demonstrating awrah in public (awrah for men is the area from the navel to the knees). Fourthly, Islam prohibits the mixing of outsiders women and men in the same room without special need. Fifth, Islam forbids music. Sixth, Islam prohibits assimilation to the infidels in their inherent habits, this applies to both modern infidels and infidels of the past, even if something is presented as a "folk tradition", which was somewhere before the representatives of the nth people / tribe converted to Islam. Now let's look at the so-called "fighting without rules" in the light of these prohibitions. As we can see, all these prohibitions are violated in them. The blows prohibited in Islam are applied to the face. There is a risk of extremely high harm to health and there is no reasonable excuse for this harm, because all this scuffle is arranged with one purpose - to amuse the public (this is clearly a goal not approved by Islam). In battles, "athletes" go out in short shorts - the clothes do not correspond to Islam. In the room where the fighting takes place, the audience often mixes, outside men and women mix, many of whom are dressed in a way that is not befitting of Islam. The fights are accompanied by music, which is strictly prohibited in Islam. Moreover, the habit of such "spectacles" is not something that Islam teaches, not an Islamic tradition, and not something that Islam approves of. Rather, it is something that some people who formally consider themselves to be Islam, borrowed from modern infidels and from their own and other people's pagan ancestors, who alone can / could encourage such spectacular cruelty (the UFC today is a clear analogue of gladiator fights in pagan ancient Rome ). Islam has nothing to do with this barbarism. Fighting without rules, boxing and everything like that in Islam is prohibited not only for children, but also for adults. There is no difference between children and adults.
It is worth noting that Islam permits and even encourages health promotion. For these purposes, it is recommended, for example, to practice swimming. You can also host running competitions. A senseless scuffle on stage does not aim at improving health in the first place. The purpose of this massacre is to arrange a spectacle for the amusement of the audience, who rejoice in the sophistication of violence. To rejoice at senseless violence on stage is a property of infidels, not Muslims. It is a pity that many people who call themselves true believers began to forget about this.
The general attitude of Islam to sports is normal, permissible, but here several parameters must be taken into account: first, strict dogmatic Islam believes that sports, first of all, are needed for the person himself, to maintain his physical qualities and health. Secondly, it is bad to go in for sports and participate in competitions for money. In the orthodox view, sport is an activity that does not imply commercial use. On the other hand, now in many Muslim countries, which are distinguished by strict morals, the Olympic movement is actively developing, and even Iran has Olympic champions. Thirdly, the sport must develop in such a way that no wagers or bets are allowed. This is excitement, and the attitude towards gambling in Islam is negative.
Moreover, one should not allow the ultimate competitive element, the desire to defeat an opponent, because such sentiments are not welcome. In Islam, sport is a game, and it should be treated as a game where someone loses and someone wins. The desire to defeat an opponent by any means, to cultivate aggression in Islam is not welcome.
I have not seen any special instructions about children's participation in sports competitions, but here you can proceed from reasonable ideas. This is a blessing if it relates to children's physical development.
If we are talking about Chechnya, then we must understand that it is not Islamic principles that operate there, but local traditions: the guys ride horses, wield cold weapons, are engaged in martial arts and there are no tennis players among them. These are normal traditions, and let it be better for young people to go in for sports than anything else.
However, when participating in sports activities, from an Islamic point of view, a man must hide the area between the navel and knees. When I was teaching at an Islamic university in Saudi Arabia, before going to the pool, for example, I was asked to buy a special swimming suit - these are such tight breeches below the knee.
But when children take part in such competitions without protection, here, of course, doctors should have intervened and the competition had to stop immediately.
Spectacular sports are defined as permitted or prohibited after all their advantages and disadvantages have been correlated. If there are tangible advantages in a sport or game, then they are allowed and even desirable, and if a particular sport is more harmful than useful, then it can be considered prohibited. Prophet Muhammad, peace be upon him, directly approved the competitions of wrestlers, archers, spear throwers, etc. and sometimes he himself participated in wrestling martial arts
Of the provisions of the Sharia, which make a certain sport prohibited, one can single out a ban on strikes that can harm the opponent. Accordingly, sports such as boxing, karate, etc. are not approved by the Islamic religion.
Children's participation in sports is also viewed through the prism of the advantages and disadvantages that they acquire