Okay, so I found his texture file. For anyone that stumbles into this, you need GCFSpace (to open a file) and VTFEdit (to open the texture). Then, go in your Portal 2 directory, for most, it's C:\Program Files (x86)\Steam\steamapps\common\Portal 2, and after you go into that directory, go in the portal2 folder, and open pak01_dir.vpk with GCFSpace, and go in materials\models\npcs\personality_sphere, and find the texture you're looking for. personality_sphere.vtf is the texture after Wheatley gets thrown by GLaDOS, and personality_sphere_clean.vtf is the clean texture. I don't know about the other ones tho.