@PlayLikeLars - Spawners

Old:

/setblock ~ ~1 ~ minecraft:mob_spawner 0 replace {EntityId:"Zombie"}

/setblock ~ ~1 ~ minecraft:mob_spawner 0 replace {SpawnPotentials:[{Type:"Skeleton",Weight:1,Properties:{SkeletonType:1b}}]}

New:

/setblock ~ ~1 ~ minecraft:mob_spawner 0 replace {SpawnData:{id:"Zombie"}}

/setblock ~ ~1 ~ minecraft:mob_spawner 0 replace {SpawnPotentials:[{Weight:1,Entity:{id:"Skeleton",SkeletonType:1b}}]}