vernal nova
You can make friendly fights in the butterfly mansion (Or another place idk), for that you must be with another person in the place and accept the fight.
While the fight is active, no one can interrupt the fight which means that people outside the fight can't attack you and you can't attack them, (Finally, no random will come to to intervene in 1v1... It can also be useful in case the rank system is maintained, so not all of us will have to press F hard since a Auto aim skill can hit us and they lose their attack).
This can include selectable settings such as how many people versus how many, level scaling, remove hunger system during the fight, remove dying penalty, teammates don't hitting each other, etc.
Edit: The place would be flat and big, that would make the fight more comfortable
normal fjord