You don't really need any skillups except on valkyries. A five cd Valk used to kill Heavy Metal Dragon is near guaranteed to be up by the time the final wave's shield is down after Awoken Ammy hastes.
You also only need like one double/triple donger at +99 ATK to get through the super kings.
Elia isn't that good as she'll gain like 10 levels through the dungeon.
Assuming that Awoken Ammy is +297, you can stall infinitely on most of the pirate dragons, the purple shields (if you isolate one). You can also use subattribute damage to kill pengdra/small dragon waves to preserve light orbs for later.
I absolutely- do recommend Sandalphon (or shynee), as you pretty much need to kill Zaerogoo in one go.
I would say LZL, Valk, (Damage Enhance), Unicorn Rider, Genie, Amaterasu.
Just save Unicorn Rider for the boss to get more valk ammo and have at him.