I tried this sort of stuff last year. I mean, finding and playing every japanese game for some consoles.
Let me tell you right off the bat: most of those games suck. I don't remember most of the GB ones, but here's the ones I liked:
- Harobots: kinda like a Pokémon game, but you play with Sunrise mechs
- Robopon (Robot Ponkottsu): Pokémon with mechs. Really, even the interface is mostly the same as Pokémon's.
- Sakura Taisen GB 2: there are two games, but I only played the second one. You're a new transfer (can choose to be a guy or a girl), and you go around missions helping Oogami. The cast of the series returns (at least the first series), so you can consider this some kind of side-story. There are both adventure/VN parts and battle parts. Kinda like Sakura Taisen 1. They even have the LIPS system.
- Super Robot Wars Link Battler and 2G. 2G is a remake of SRW 2 with G Gundam and V Gundam characters, Link Battler is kinda like Pokémon the Card Game.
- Toshinden: a fighting game on the GB? Yeah. Movement is pretty good for its limitations, and they even have remixes of the characters' themes.