Gone with the wind
This flying-type move, unusable since Gen 8, brings the target to the sky, making them unable to attack, then drops them the next turn, dealing damage.
What is Sky Drop?
This water-type move, unusable since Gen 8, restores 50% of the damage dealt to the user
What is Bouncy Bubble?
This move, unusable since Gen 8, prevents the opponent from switching out
What is Spider Web?
This pure grass type pokemon is unavailable in Gen 9. Perhaps it might have been relatively useful in a sun team, given both its abilities, excluding its hidden one, benefit from sunlight. In sunlight, it can either get double speed or immunity to status conditions.
What is Tangela / Tangrowth?
This move inflicts damage and has no secondary effect. Its power and type depend on the berry it is holding, and will consume the held berry, failing if it is not holding a berry.
What is Natural Gift?
This flying-type move, unusable since Gen 8, uses the last move targeted at the user by a Pokémon still on the field
What is Mirror Move?
This move, unusable since Gen 8, traps the opponent and damages them for 4-5 turns, functioning like a physical version of whirlpool
What is Clamp?
This bug type move, unusable since Gen 8, raises the user's special attack by 3 stages
What is Tail Glow?
This damaging physical move also drains HP from the opponent each turn. It's basically a base power 90 leech seed, no wonder it can't be used since Gen 8.
What is Sappy Seed?
This move makes the attack on the next turn always result in a critical hit
What is Laser Focus?
This flying type pokemon, not usable in Gen 9, has an ability that lowers the accuracy of status moves used against it to 50%. This is not its hidden ability.
What is Sigilyph?
This water-type move, unusable since Gen 8, has a 10% chance to lower the opponent's speed
What is Bubble?
This bug type move, unusable since Gen 8, is like a bug version of ancient power
What is Silver Wind?
This grass-type move, unusable in Gen 9, has a 50% chance of lowering the target's accuracy by one stage, and it isn't blocked by bulletproof.
What is Leaf Tornado?
This normal-type move's power increases with higher friendship. But just like its opposite counterpart, frustration, it is unusable since Gen 8.
What is Return?
This flying-type move, now unusable in Gen 9, always confuses the target (at least in Gen 8 it did)
What is Chatter?
This water-type move, no longer usable in Gen 8, is the only water-type move with a chance to paralyze
What is Splishy Splash?
This bug type move, unusable since Gen 8, is the only bug type move with a chance to flinch
What is steamroller?
This grass type move that puts the opponent to sleep is unusable since Gen 8. Though I don't know why you would use it anyway, given its 55% accuracy.
What is Grass Whistle?
This normal-type move, unusable since Gen 8, has a greater move the more HP the target has
What is Wring Out?
This flying-type move, unusable since Gen 8, has 90 base power and a 30% chance to flinch
What is Floaty Fall?
This water-type status move, unusable since Gen 8, lowers the damage of fire-type moves by 67% in both sides of the battle
What is Water Sport?
This pure bug type pokemon, unavailable in Gen 9, had a hidden ability which ensures all attacks, both incoming and outgoing, will always land
What is Karrablast?
This move is not usable in Gen 9 because it is a G-max move. In fact, it is Rillaboom's exclusive G-Max Move which ignores the opponent's abilities.
What is G-Max Drum Solo?
This move, unusable since Gen 8, makes the user endure 2 turns before striking back to cause double the damage taken
What is Bide?