How to make a Dragon

Hello everyone!

I have been struggling the past 24 hours with getting a dragon to work on my server in the Overworld.

Here is his current config:
Dragon:
Type: GHAST
Display: '&cDragon'
Disguise:
Type: 'ENDER_DRAGON'
Health: 200
Damage: 30
BossBar:
Enabled: true
Title: 'Dragon'
Range: 20
Color: RED
Style: SOLID
CreateFog: true
DarkenSky: true
PlayMusic: true
Options:
MovementSpeed: 0.4
KnockbackResistance: 0.99
Despawn:...

How to make a Dragon