This will spawn a normal iron golem, but when it fights mobs...
Note: Minify the command to avoid issues :)
Indestructible Zombie!
Healthiness drink!
Speediness of Doom!
The Greedy Guy
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)