I'm not familiar with that model but based on the picture, Composite (RCA to BNC adapters on Video A & B) and S-Video (Y/C on Video B) are your only two options. PS2 and GCN OEM S-video cables would be the way to go. SNES S-video cables are pretty easy to come by (just avoid any that include the yellow composite plug because they're not really S-Video cables). Genesis is a little different, I think it needs to be modded for S-video and it's composite is terrible. My only experience is with my OG model 1 though.
Spend some time researching here:
https://www.retrorgb.com/systems.html
All of that said, there is that covered blank section above the inputs that may indicate an ability to display a version of RGB with an additional input card.
edit, and yeah what they said, lol