Can I have Gogo assigned skills for everyone?

First what do you mean by "empty commands" ? And do you mean "having the fourth slot available to most characters to pick a slot command" ?

Edit: Ok, I think I understand now. To make other characters access the special menu where you choose your commands, you need to add conditions in several places in bank C3 for each character you want to have access to the special menu. It's just after that a matter of rewriting code to fit the extra code (checks). Character having access will have the option to change all 4 slots though. I am unsure on how to make this option for only slot 4 but it would still be done in bank C3, it's a matter of understanding how the game differentiate the slots...