This part is a shortie
Celestibun, slightly coming out of it's shadow, fears Issac, a flashback dashes through its mind. Issac used to own Celestibun, he treated all of his pokemon badly. Especially Celestibun, it was eternally scarred because of some of Issac's actions...
Celestibun fled.
It felt freedom.
But it realised...
No home now...
It went wild.That is Celestibun's backstory...
It hid behind Twizzlepop, Twizzlepop notices and tries to comfort Celestibun.
When the battle ends, Maddison loses leaving her in a hopeless state. Little did she know, this wasn't going to be the last time she saw Issac.