GameCube and PS2 are a breeze to set up. I never use RetroArch for either of them, all you need to do is set the bios for PS2, change the input (AYN will automatically be set, but I find its better safe than sorry as it can make the odd error when configuring input for you!), choose your upscaling and go!

GCN was even easier, input and upscale, then play!

I’ll be writing up a thorough guide/games/settings post, I’ll find you an link you when I do if you’d like? But for PS2 and GCN its the work of 2 mins at the most on each :)

No RetroArch. At all.