Visually spruce up dragon fight

I'm planning on making a custom ender dragon fight, I wanted to do some cool things to make it unique like have the dragon be ghostly (invisible and on the same team as the player) and larger than normal but have been foiled with both. Don't think you can change the dragons scale attribute or give it potion effects. Any ideas for other stuff I could do to make the dragon look different? I am planning on making it do custom attacks by summoning invisible guardians/withers/projectiles etc And maybe try do some visual stuff with particles...