Difficuly most not be peaceful,
Block below must have a solid surface and not be bedrock, barrier, trapdoor or glass.
The block above must be transparent and then mob must be immune to effect from the block below,
In the Overworld and End light must be zero,
In the Nether light must be 11 or less.
Hover for mob specfic info:
Blazes spawn only in Nether Fortresses in the Nether
Only spawn in overworld, they can spawn with a trapdoor above them, becuase the are shorter than zombies or skeletons
Drowned only spawn in the overworld, spawning block and block below must be water. In a river 1/15 chance, in oceans 1/40 and must be at least 5 blocks below sealevel. Can also spawn in dripstone caves
Require 3+ because there are tall, can spawn in any dimensions
Ghast only spawn in the nether and have a 95% of spawn failure. Spawns only in nether wastes, soul snad valley and basalt deltas biomes
Spawning Block and Block below must be water, allows waterlogger and bubble columns, 95% chance of faliure if exposed to the sky, this is to make more spawn inside the monument
Can not spawn on nether wart block and only the Crimson Forest biome
Only spawn in the desert where exposed to the sky
Only spawn in Nether Waste or Basalt Delta biome
Only spawn in Nether Waste and Crimson forest, can not spawn on top of netherwart block
Only spawn in the Overworld or in the Soulsand Valley, or in Netherfotresses, spawn less in cold caves
If spawning in a swamp biome must be on level 51 thought 69, and the chance of a succeful spawn increases the fuller the moon is. If in a slime chunk then it must be below level 40
Only in Overworld
Only in cold biomes with skyaccess
Spawn in the overworld, only they can spawn in thier huts (besides the cats)
Spawn in the overworld, spawn less in desert caves
Only spawn in Netherwaste and Crimson forest biome, cannot spawn on nether wart block