Help with skills to GUI slots

I need some help with making adjustable slot skills. For example, I want to make it so If I select a skill, I can choose to pick the available options I made on the skill list so I can pick what skill goes in said slot. This is for a One Punch man mod BTW I started a day ago so not too far into it besides creator creation and GUI stuff and base attributes. I imagine I can achieve this by making a bunch of separate global variables for each slot, so they save when u leave. But I am wondering if there is an easier way of achieving this.

Here is a the video link: https://imgur.com/ZLjRhyu