I don't know if this would be useful to anybody but I got sick of picking a monster transformation only to learn that it didn't know windmill, so I made a list of all the transformations my milletian has that know the skill.
He doesn't know them all yet, obviously, but he has around 270 different forms under his belt and that's a good number for a list.
Hope it helps with choosing what to hunt.
F Spider
E Wild Horse
E Wisp
E Goblin
D Pumpkin
D Kobold
D Bandit Imp
D Imp
C Bandit Goblin
C Skeleton
C Rat Man
C Bandit Human
C Flying Sword
B Mini Skeleton
B Shadow Shire
B Bandit Giant
B Sahagin Fighter
B Zombie
B Shadow Wizard (F)
A Zebra
A Corrupt Alchemist
A Zombie Soldier
A Sahagin Warrior
9 Eagle Owl
9 Unicorn
9 Pot Warrior
9 Werewolf
9 Ghoul
9 Ant Lion
9 Fighter Slate
9 Alligator
9 Spider Wasp
9 Gnoll
9 Desert Ghost Fanatic
8 Snowy Owl
8 Stone Zombie
8 Ixion
8 Beetle
8 Snow Spider
8 Phantom Mask
8 Tarantula
8 Desert Warrior Ghost
7 Trade Assistant Goblin
7 Ghost Armor
7 Shadow Wizard (M)
7 Python Shaman
7 Desert Spider
7 Pot-Belly Spider
7 Sulfur Spider
7 Spike Laghodessa
7 Stone Imp
7 Mummy Servant
7 Hobgoblin Warrior
7 Golem
7 Dark Commander
6 Masked Goblin
6 Blind Crab
6 Llama
6 Forest Mushroom Spider
6 Goblin Keeper
6 Dragonfly
6 Bandersnatch
5 Goblin Swordsman
5 Phantom Tableware
5 Candle Spider
5 Armored Skeleton
5 Ornata Spider
5 Spider Fighter
5 Wight
5 Zippy Nipmore
5 Wild Troll
4 Scarecrow
4 Goblin Sword Master
4 Santa
4 Stone Mask
4 Chandelier Spider
4 Sickle Laghodessa
4 Candle Warrior
4 Shrieker
4 Forest Golem
4 Lost Sahagin
4 Snow Zombie
4 Hobgoblin Exorcist
4 Guardian Horse of the Ruins
4 Giant Hornet
4 Sea Troll
4 River Sahagin Fighter
4 Prison Zombie
4 Skeleton Ogre
3 Tabhartas
3 Snow Imp
3 Saturos
3 Troll
3 Skeleton Armor Ogre
3 Lizard Witch
3 Glowing Stone Zombie
3 Ogre Warrior
3 Cave Sahagin Warrior
3 Ruins Guardian
2 Skeleton Full Armor Ogre
2 Cave Masked Goblin
2 Snow Troll
2 Goblin Hunter
2 Skeleton Squad
2 Pirate Skeleton
2 Snow Golem
2 Dullahan
2 Sulfur Golem
2 Crystal Golem
2 Incubus
1 Succubus
1 Siren
1 Banshee
1 Demi Lich
1 Arc Lich
