Question about "Textures" Power Discs

Do you have to have, say, the Finding Nemo Textures Power Disc on the reader in order to use any of the Nemo textures in the game, or is it just used exclusively to convert every piece of terrain to that theme (as we've seen in videos so far). In other words, are the Textures Power Discs the only way to get, for example, trees from Nightmare Before Christmas or components from Sugar Rush in your Toy Box?

this is a good question. purely based on what we know so far, my best logical guess is that the texture discs are used to unlock said things, but have the option upon placement to overlay everything in case that's what you wanted to do.
so let's say for example you wanted a nightmare before christmas tree. you would place a normal default tree of your size liking first, then use the editing wand to then 'paint' it the theme that you want. that way instead of cluttering your menu with 100s of trees, it's just the different size and shape trees that can then be skinned to the various themes.

i totally hope that you can use the trees and textures outside of having the discs as it would be less limiting to the disc nature of the game, but then there's not much desire to hunt for the discs themselves. unless they'd be more common than the mounts which is totally possible.

there's my analysis

I've been wondering this too, ever since I first read about power discs. If it's only to create an overlay of the world I am going to be so disappointed.

A texture power disc only overlay the textures and stuff. So they don't give you new items.
Like a tree + Sugar rush = Candy tree
Or tree + Tron = Tron Bill board.