do you think any classpects would be capable of power-copying? a thief or a rogue would be the natural choice for the class but i cant come up with any aspects that really work

I don’t really know about power-copying, but I have argued, for copying God Tier powers, the most likely option would be a Thief of Heart. Power Copying is a Thief Skill though, Rogue as well- We see Condy actually stealing the powers of the entire Troll Caste.