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Wasn't sure where this was supposed to go but in Team Builder for VGC2021, Gastrodon is showing Sludge Bomb as illegal although it can learn it in-game/shows available under VGC2020.
BUG STATUS: FIXED by Kris
If we do Monday, I might not be able to play until 8pm my time, but we can try. If you do decide you want to play Sunday, I'll just idle on PO for a while.