Dark Arms is an Action RPG developed and published by SNK for the Neo Geo Pocket Color. It was somehow rated E by the ESRB despite being chockful of Satanic imagery and bloodstained oubliettes. It takes its name from SNK's older arcade title Beast Buster which I haven't played it, but I see it's on SNK's 40th Anniversary collection for Nintendo Switch, and I hope to get that soon. DA is a top-down character action shooter that incorporates monster-catching elements, likely driven by the contemporary Poke-Mania.
In addition to its single-player story mode, Dark Arms features two-player versus action using a link cable but I don't know anybody else in SouthEast Pennsylvania with a NeoGeo Pocket and a copy of the game so that is likely to remain untested. If I go to Magfest next year though I'll bring it and maybe try to link up with someone there.