I think they had a proper discussion about banning it but ended up neglecting updating their lists all over the forum and sites.
I'm finding a lot of other pokémon that aren't in the list, I'll update the OP in a few minutes.
Yes, since both Walking Wakes and Iron Leaves are allowed in National Dex OU at the moment.
If the tournament starts while they're still legal, players that had them in their teams will be free to use them throughout the tournament.
If they get banned before we start the tournament some extra time will be given for people to edit their teams.
But if something like that happens while the tournament is ongoing we'll have to ignore the change.
I'm trying to put out a blog post this week that will serve as an introduction to competitive pokémon!
In the meanwhile I'm always available to try explaining the basics of the game in private. Mikey also seemed to offer some help in teambuilding.
Keep in mind that copying sets that you find in the internet is perfectly fine and somewhat encouraged for the least experienced players.