I'm slightly surprised that shift gear wasn't mentioned, +2 speed and +1 attack sounds threatening on a BO mon like Great Tusk.This is what I'm thinking for a starting banlist:
Definately Banned:
Pokemon
Arceus
Baxcalibur
Calyrex-Ice
Calyrex-Shadow
Chien-Pao
Chi-Yu
Deoxys
Deoxys-Attack
Dialga
Dialga-Origin
Eternatus
Flutter Mane
Giratina
Giratina-Origin
Gouging Fire
Groudon
Ho-Oh
Iron Bundle
Koraidon
Kyogre
Kyurem-Black
Kyurem-White
Lugia
Lunala
Magearna
Mewtwo
Miraidon
Necrozma-Dawn-Wings
Necrozma-Dusk-Mane
Ogerpon-Hearthflame
Palkia
Palkia-Origin
Rayquaza
Reshiram
Shaymin-Sky
Sneasler
Solgaleo
Spectrier
Urshifu
Urshifu-Rapid-Strike
Zacian
Zacian-Crowned
Zamazenta-Crowned
Zekrom
Falinks
Gholdengo
Hoopa-U
Komala
Lilligant-Hisui
Regigigas
Smeargle
Moves
Baton Pass
Belly Drum
Last Respects
Quiver Dance
Revival Blessing
Shed Tail
Shell Smash
Rage Fist
Abilities
Arena Trap
Contrary
Huge Power
Magnet Pull
Moody
Neutralizing Gas
Pure Power
Shadow Tag
Sheer Force
Speed Boost
Stakeout
Stench
Unburden
Water Bubble
Items
King's Rock
Razor Fang
Watchlist:
Pokemon
Frosmoth
/
Kommo-O/Numel (At least one banned)
Manaphy
Persian-Alola
Slaking
Veluza
Zamazenta
Moves
Boomburst
Abilities
Poison Heal
Items
Damp Rock
Heat Rock
Also with Falinx and Liligant-H being banned, I think it's a bit fairer to ban the moves that make them overpowered instead of the pokemon themselves, because then they are a lot more balanced.
Also if Numel gets banned, I already have watched enough Dracomenace videos to know that simple beam + trace on another mon is very dangerous.