Trevenant desync

[Ulquiorra 1]

I battled the same player few times and he had a Trevenant (with Frisk). Whenever it went out for battle, the game would desync. He had Confuse Ray and confused my pokes often, but when my poke hits itself from confusion, it successfully attacks at my opponent's side. For two times, I used Flamethrower with my Delphox to OHKO that Trevenant before it could attack. Either it fainted at my side and survived at my opponent, or other way around. Also, if it happens that Trevenant faints only on one side, the game hangs forever waiting for opponent move.

 

Hopefully I explained it clear. Today it just happened 3 times in a row, so I thought I'd report this.