Rare moment of Sunny not being super happy and innocent, she is in serious mode. This is why you don't piss off the nice ones.

Sunny is a young Charmander girl who is also a time-traveler originally born in the ancient past but displaced by a Space-Time Distortion to end up in the present world. Sunny was too young to remember the world she came from so she has no connection to the world she left and is perfectly happy living in the current era. All except for the fact that her Immortal Tyrant Father has started a new war across the world to try to break free of the seals placed on him by the Legendaries, and wants to usurp Arceus and create a new universe in his own image.

Luckily Sunny is not alone.
Always at her back is her guardian, mentor, and friend Noctis the Gastly. In life Noctis was the Archmage of her father's court, but he was executed as a traitor for conspiring with the Legendaries to undermine and defeat the Forbidden Tyrant King. He failed in his lifetime but he is not finished. He came back as a Gastly and has been tasked with raising Princess Soleanna (Sunny).

Originally it was just a job for him, but he has grown to care about Sunny and protects her fiercely. He is encouraging and supportive of her, he enjoys telling stories with great dramatic flare, and he can also be a little mischievous and cheeky. Around other Pokemon especially ones he is typically quiet and observant, if addressed he will be serious and polite.

For Sunny's sake, he will show mercy and restrain as to not expose her to too much brutal violence, but if she is passed out then he'll give you a reason to be afraid of the Dark! He maintains memories from his previous life and while being reduced he is still a very powerful Shadow Sorcerer, which compliments very nicely with Sunny's Light Magic. I actually started to think about how Shadow and Light powers could mix; I imagine Shadow can't hold back all of Light's radiance causing it to come out filtered through darkness as a rainbow, but they can control it to have the properties of shadow and Light at the same time.

Shadow magic is malleable, flexible, able to shaped into any shape of form you can imagine.

Light magic is intense, it radiates and wants to spread, and it can be soft and healing or sharp and burn through almost anything

Together they have a power that they can shape and use for just about anything they can imagine so long as they are working in unison.