Older devices (GL2/OpenGLES2) cannot use glcore, since it needs at least GL3/OpenGL3 to work.

Can you elaborate on that sentence above, though?

Some cores need a specific OpenGL and/or Vulkan version to work and if the front-end driver (i.e. RetroArch's) does not support that version, the core won't work.
For instance, Flycast can be compiled for Vulkan and when started will request a Vulkan context from RetroArch. But if RetroArch doesn't support Vulkan, the core cannot start and the emulation stops.

@lukePi-0 you shouldn't be adjusting the retroarch video driver in this circumstance. info on HW rendering in duckstation are here: https://retropie.org.uk/forum/topic/30743/lr-duckstation-experimental-new-playstation-1-emulator - you cannot use duckstation HW rendering on a pi3

i believe lr-pcsx_rearmed has a core option to remove dithering.

@mitu Quick update: lr-pcsx-rearmed and lr-parallel-n64 worked.

The naming depends on the device-tree settings, doesn't affect the actual capability of the GPU. Running the same command on a recent Raspbian OS yields

Graphics: Device-1: bcm2711-vc5 driver: vc4_drm v: N/A bus ID: N/A chip ID: brcm:gpu

RetroPie doesn't support Manjaro OS on the Pi, btw.

lol fixed it. So apparently I didn't have to edit the retroarch.cfg file I thought I had to, which was the one under config/retroarch/config. The one I had to edit was under "all", some sort of root directory not accesible through the File Manager. I had to use the Configuration Editor to make the change. Initially I had tried using the editor within File Manager (nano).

Okay, I figured out the solution... even though all other ROMs i've tried are european they still work with the american BIOS... but only Bugs Bunny and Taz don't.

I'll only use USA roms from now on.. The screen doesn't jump with USA version of the game

There should be no library issue unless you do not use an official image or your RetroPie-Setup script is not up to date.

You can also do a binary update. I don't know how old this binary is but it should be newer.

@actnash Also, just wanted to say that for the pi 1, quicknes and pocket SNES are the two emulators that are working great for me. Yoshi's Island runs almost full speed, with occasional stutters, but super mario world runs flawlessly. For NES, OpenGL driver, max swapchain= 1, video hard sync on =0, and frame delay=8. I got a NES classic for Christmas, but with these settings on the pi, it's very hard to tell the difference between the two. Graphics, input latency, and everything else is very comparable which is AWESOME. For SNES, Max swapchain=2 and frame delay=4. Turbo overclock makes all the difference for SNES.