A boss weaker then ED or WB.I'll edit this soon if it doesn't work.
Note: Minify the command to avoid issues :)
Flying Machine in one command!
Space Walkers in one command!
Gravity Gun in one command!
WitherDragon!
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)