Before you read this, I suggest you look at this(it is information about Starstrike)

Starstrike, the Ethreal Dragon Pokémon.

Given the nickname Starla by Lillie for how it reminded her of the stars and the resident dragon type pokemon of space, Rayquaza

Ghost and Dragon type

It is genderless(but is often referred as female)

Not much is known as of its history or its relations to Necrozma or the other Ultra Beasts

It is long and serpentine. It has green scales with a lavender purple hue. Long neck and avian like head. It can use Z-Moves(Shimmering Star Supernova using Strikium-Z) as well as Mega Evolve(Starite). It's mega evolution slightly differs from its normal form. It now has large green wings and golden yellow "ribbons" on its tail. After a Mega Evolution, it still retains the wings from the ME(short for Mega Evolution) and now has four legs instead of two(can walk on two legs or four with ease). It reverts to its original form after Mega evolving a second time. Very intelligent and smart. It also has two long feathers on its head too.

It has no known allies(later in book, it will side with the Ultra Guardians and eventually be caught by Ash)

Known moves:

Dragon Pulse

Shadow Sneak

Shadow Ball

Draco Meteor(all moves used against the Ultra Gaurdians when they meet it the first time)