Using an illegal Pokémon results in a game loss being rewarded to the person who used the illegal Pokémon. We made it clear in the announcement (quoted above) that these Pokémon were not allowed this round. In addition, tournament rules and historic precedent, which is based off of the aforementioned rules, dictate that anything released or dropped in the middle of a round is not legal until the following round.
Given this, game one would’ve been a game loss for choicebandkyurem regardless, but he lost the game as it was played and then won the next two without using anything illegal. Any arguments about it impacting team choice are entirely moot and null as it is on people to know the rulesets they are playing, so the other games, which were played under perfectly legal and normal circumstances, stand.