If anyone already pointed this then this post is pointless, I’m posting because I couldn’t find an open post to reply.
Citra version: Canary Build - 68fce6e
Game: Pokemon Ultra Sun
It is a known bug that happens after you beat the League, game freezes when you enter the Hall of Fame.
One solution was to go through the whole process with only 3 pokemons.
I saw one guy going on Pokemon Sun with 3 pokemons and CPU JIT disabled and other one saying that going only going with 5 pokemons it would still work.
I was able to go with 5 pokemons and with CPU JIT disabled.
I think it would still work only with CPU JIT deactivated (I can’t test, game saved after the credits).
I don’t know if it only works with Pokemon Ultra Sun or for all versions (U-Sun/U-Moon Sun/Moon).