Whenever I type the /summon minecraft:axolotl [pos] {Variant:"mavm"} no matter what name I put in the brackets it just comes out as the pink one, the only thing I am doing differently is changing my coords in the [pos] section. And it won't let me type it with bracets so I take those off. But nothing is working. I play on version 1.20.1 so the old way of summoning wouldn't work either. Any help would be appcitated.

Yes exactly like that but instead it's like your commands, like your variants like Shulk or wilder

/summon minecraft:axolotl ~ ~ ~ {Variant:"mavm:skulk"}

/summon minecraft:axolotl ~ ~ ~ {Variant:"mavm:wilder"}

Will just give an example
/summon minecraft:axolotl ~ ~ ~ {Variant:"minecraft:blue"}