I've tried the GC controller for quite a while, and here are my experiences:
1.Super Mario Odyssey
Just as I expected, you can only use the tiny little Z button to crouch. And since the crouch button is used very frequently when you wanna do all kinds of movements in Odyssey, you'll fint it not as easy as when you use a pro controller or even the joy-cons. After all, the game isn't designed for this controller.
I was thinking that Forces doesn't really need the shoulder buttons when you play as modern Sonic, and I gae it a try. Then I found it quite awkward cuz you can only use the B button to jump, and it's nearly impossible to manage B and Y together with a single thumb. Geez, the button layout of GC controller does bring quite some problems to those non-GC games.
Since Mania doesn't use a lot of buttons, it's pretty fine using a GC controller, but it just feel pretty much the same as using othe controllers. It won't let the GC controller's uniqueness stand out.
4.Shadow the hedgehog
I finally gave up using it on the switch and moved on to actual GC games emulated on PC. Dolphin emulater fully supports this controller, of course, and I tried Shadow the hedgehog out since it's the only GC game I've already downloaded. It feels pretty good, though the game does get pretty frustrating when you have to go on an enemy hunt. Next.
5. Sonic Colors
As a Wii game, this game also supports the Gamecube Controller. And it worked out pretty well. Finally a game that enables me to make the most out of this controller I use. I know it's gonna be useful in Mario Sunshine too, but I have yet to download it. I'll try it out later when I get it downloaded.