lol what the fuck
battle parse:
http://pastebin.com/raw.php?i=HPayd0mr
I can't give you an accurate turn by turn of what happens, but it's pretty obvious what does happen.
http://www23.atwiki.jp/pkmnbw/pages/166.html -- there's more bugged videos here.
「665222127416」「320280020859」「723898027648」
I don't speak Japanese, but it's pretty obvious that the game sends out the fainted Walrein which doesn't show up because it is fainted. The game still thinks there is a Pokemon on the Subway Trainer's side and continues the battle, but every turn it acts as if the Pokemon was just fainted.
That said the switch instruction looks fine itself, but the game shouldn't be allowed to do that. I don't know how this glitch was done, but that's how it plays out!
other resources here