@sugo98 I ran into this same issue. After 3 hours of head-banging, I managed to solve this, thanks to your post that gave me a hint: 5th joystick.

For some reason, this game wants the Slot 2 to be plugged in. So it actually requires 5 players, the 5th one being in fact the Player 2. So you just need to tell RetroArch that Port 5 is controlled by the same gamepad as Port 4. Make sure this 5th player is set to a PlayStation controller or analog pad and it works.

This seems to be the same behaviour among all KCET football games. And maybe Track 'n field games too?

I hope it'll help you.

@Solid-One Thank you for your reply. It is interesting that you had no issue with the same game using an earlier version of RetroPie on a Raspberry Pi 2. I have submitted a report at https://github.com/libretro/pcsx_rearmed/issues/350 as you suggested.

@megaJekan I don't use bi-linear and my monitor is a PC CRT (VGA converter). I would say it looks ok, not spectacular or good. Especially Arcade games are problematic, but that is another story. On the PCSX-ReARMed I use the Shader "scanline.glsl" (Filter:Linear, Scale:Don't care) from emulators SHADERS menu. Honeytly, this does not look that great, but it is the only one working so far. On some other consoles I even use the "sharp-bilinear-scanlines.glsl". On the PSX some games look great with that sharp one, but some others are ugly. Crash Team racing is unplayable ugly with the sharp one, thats why i use standard scanline shader. I suppose it have something to do with different resolutions used by the games.

Over at GitHub, they recommended downgrading to a previous version. How can I go back to before 1.6.3 PPSSPP?

@mrbwa1 I know, but when you turn the resolution down, people claim it works. I'll use a display with a very low resolution so I'm fine with turning the game's resolution down. But thanks anyway :)