The best Japan-exclusive GBA (Game Boy Advance) non-RPG action games?

[Restart_Point]

So that would be Japan-only Shooters, 2D / isometric / overhead / side-on scrolling Run'n Guns, Beat'em Ups, Hack'n Slash etc. (I have found all the western ones and all the FPSs).

Shmups are my favourite genre but I have found all of those now, so looking for action games like above, they are harder to find by googling as general Japanese recommendations on forums etc. seem to be 99% RPGs on the GBA. Any suggestions would be greatly appreciated by my Everdrive, thanks!

[Sumez]

I can't really think of many JP exclusive GBA games in the first place. At least, not ones that aren't shovelware or super text heavy like you said.

One weird one I came across surprisingly just browsing a bargain bin at a local shop here in Denmark, is Metalgun Slinger. A game I'd literally never heard about before. It's a Mega Man-like, or more specifically a MMZ-like, so it qualifies as an action game that's playable without understanding Japanese (even though there's quite a bit of dialogue). It's not a great game, but it's interesting at least.

Mr. Driller Ace (or "Mr. Driller A") is probably the best handheld Mr. Driller, and one of the better home versions of the series, unlike the frankly abysmal DS game.
It's a puzzle game, sure. But I think when you get really into the meat of it, it also qualifies as an action game.

Bomberman Jetters: Densetsu no Bomberman is an action adventure style take on Bomberman, similar to Bomberman Tournament. Basically, Bomberman Zelda. I guess it's borderline an RPG, but it has action gameplay and is fairly enjoyable.

[Restart_Point]

Thanks for those, Metalgun Slinger looks like exactly the kind of thing I was after.