How did he manage to blend all the subtools so good?
https://www.youtube.com/watch?v=JL75R0K_j7g
Go to 18:53
Every time I add the same material, color to my subtools they differ how can I fix this?
I assume you’re talking about subtool dimming. You can change this a couple of ways.
Turn on polypaint for all meshes (shift+click on the paint brush icon in your subtool list). Or just turn off the dimming.
Preferences>Edit>Inactive Subtool Dimming