Bug with leading pokémon

[Letsgo]

Hi,

My opponent (and I) had a bug because he switched his lead at the last moment before the fight.

 

He led with a Nidokingn that i killed turn 1. I could see 1 dead pokémon in its team.

Then a second Nidoking appeared on the field. It died instantly, even though i didnt attack it. I could see 2 dead pokémon in its team.

I pmed him, he told me he already had that bug: he switched his lead at the last moment, willing to start with Torkoal.

Then, he told me he couldnt switch into his Torkoal, as if it was dead, couldnt click on it.

After a moment he tried to switch again, and Torkoal was alive. But i still could see 2 dead pokes, even though i killed only one. During the whole game, he had 1 more dead than the number i killed.

He sacked all his pokémons, and while i could see 6 deaths, his chansey was still alive.