Yeah, Ganbare Ginkun stands out for the art style alone if nothing else, but minigames where you piss on electric rail lines do push it over the edge..
Hacha Mecha Fighter is another very colourful shooter 'em up, moreso with the dipswitch set to Japanese as in this video. Maybe quite ordinary in terms of gameplay, but visually it's quirky at least. https://www.youtube.com/watch?v=A5vJjPo7084
I'd throw Boogie Wings into the mix too, it seems quite ordinary until you realise you can pick up almost anything on your hook, including elephants etc. and that when you lose your plane you start running along the ground and can leap into all sorts of other things https://www.youtube.com/watch?v=CpCEqNjbvmY
Space Bomber is another shooter with some odd cutscenes, more galxian style in that it's fixed screen. It's pre 9/11 but you end up fighting with a pair of smoking twin towers in the background too giving it a little extra 'wtf' factor https://www.youtube.com/watch?v=h3bQWFnj5VQ&t=127s