X-Gaster is a creator, and he wants the best for everyone, even if it means hurting some people.
X-Gaster looked quite similar to Classic W.D. Gaster, but in the future, he wears a purple cloak with white cloths symbolizing an "X", and he also has fierce red eyes.
In the past, when X-Tale was still alive, X-Gaster was a friendly person. He was friends with Ink, and even shared his future project plan with him: The Overwrite Button. The button that could change the entire AU in an instant. After that, he was most likely corrupted, as he suddenly got a creepy change of appearance.
Overwrite - As he created the power to Overwrite, he can most likely use it when he needs or wants to.
Creation - He is a creator, so he can create objects from sheer mental will.
Hands - He can summon hands to aid him, giving him the abilities to multitask and to take down multiple enemies at once.
Ink!Sans - X-Gaster found Ink when Ink stumbled upon X-Tale, then he followed some Creator's Essence. X-Gaster most likely trusts Ink, since he shared his future experiment with him.
X-Frisk - X-Gaster is like a parent to X-Frisk, and is very friendly to them.
X-Chara - X-Gaster is like a parent to X-Chara, and is very friendly to them