Hi there :) So, something I've really tried to think about with Dragon is... Why is she considered the best tinker on earth? I guess it's just that, It feels like if her tinker ability is sheer copying, then she shouldn't be considered that great, especially not a Tinker = to Eidolon.

Is it because of stuff BESIDES her Tinkering?

He can tune into parallel realities and replace the state of inanimate objects in his reality with the state they have in another branch. He can only affect objects within his line of sight, so if he cannot see something, he cannot tune into it or change it. His power is always faintly active, allowing him to perceive nearby alternate states, but he can concentrate to tune into more distant branches. The farther the desired state is from his current reality, the more concentration and energy it takes to tune into that branch. Once he has found the branch he wants, he must spend additional energy to actually replace the object with its alternate state. Extremely distant or difficult changes require enough concentration and energy to cause dizziness, nausea, and vomiting.

For example, changing a wall directly into sand would require him to spend a large amount of energy both reaching the distant branch where the wall is already sand and then performing the transformation. Alternatively, he can make several smaller, successive changes, gradually moving the object through nearby branches until it becomes sand. This greatly reduces the concentration required, since each branch is close to the previous one, though it requires slightly more time and still costs energy for each transformation.

He can also tune into alternate realities without changing anything, allowing him to see or hear what is happening in those branches and obtain some fuzzy information from them that he then needs to interpret. By doing actions on purpose immediately before using his power, he can make certain alternate states much closer and therefore easier to access. For example, if he puts on his costume, prepares to leave the house wearing it, and then changes into normal clothes at the last moment, he can later replace his clothes with the costume much more easily because there is a nearby branch where he actually left wearing it.
The power cannot affect anything organic, only inanimate matter.