Easter Bunny !!!
Note: Minify the command to avoid issues :)
Hostile Archer (1.9.1)
BECOME GOD
Mobs with special abilites! only ONE command! 1.8.7 (Read The comments! )
Guardian Family (1.9.1)
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)