Hi, I was hoping someone could help educate me on what the best method for handling my game's GUI would be. We're developing in Unity.
Our game is a 3v3 match-3 puzzle game with combat mechanics, kind of like Puzzle Quest. Here is an example of what actual gameplay should look like:

In order to achieve the results from that mock-up, I had just assumed we could load a backdrop and load each element on top of that. For instance:
Load a background image:

On top of that, load the "character sheets":

And on top of those, load the additional UI elements, such as the Ability Buttons, Health Bars, etc:

However, I'm very ignorant when it comes to such details. My programmer seems to be set on using 9slice to segment each piece and draw it on screen (he just had me create a 32x32 gold border for him to use). He says this will make the GUI scalable. I figured there was enough empty space between the segmented elements that we could shift them a bit to accommodate varying aspect ratios to some degree, possibly adding black bars on top and bottom if necessary (16:9 is our desired aspect ration, anyway).
So yeah, I have no idea what I'm doing and any advice would be a huge help. I'll be happy to provide additional information if necessary. Thanks!
-Woody