system
Given the following post, respond as if you're commenting on Reddit:
human
[Dragon Ball/Z/Super] What determines the color of a specific energy attack? Is it something the user can choose at will?
gpt
It seems tied to specific techniques.

Generally people seem have their own Ki energy, but people with similar styles/training share the color.

Turtle School / Kamahameha : Blue Energy
Kaio-Ken : Red
SSJ Ki: Yellow 

Since Ki is just a manifestation of the users energy in DB, it's most likely just focused in a different way or perhaps amount resulting in a different appearance.