Will Beach Buggy Racing 2's iiRcade version ever be posted here?

Are the Game Boy + DS games emulated or were these recreated like the other games?

You can play this game for free (well, only the demo which for some reason isn't marked as such but the sequel is there too and is marked as a demo) by using the Argon service, which is also available on Android phones.

https://play.google.com/store/apps/details?id=com.markspace.retro

Well, there are plenty of homebrew games (with a good chunk of them being free) out there and several of them are notable, so this is definitely a good move. Also it's not that you can't use Sonic or Mario characters at all, it's just that it's not (legally) recommended to use them in "commercial" projects without explicit approval from Nintendo or Sega. There are plenty of free fangames out there that prominently feature both of these franchises' characters, assets, etc. and most of them haven't been taken down (in fact, in the case of Sonic fangames, Sega has pretty much endorsed them). And I have seen that you are using original characters (or at least generic ones) in games like Boulder Crash for the GBA and DS. I do understand that you may need some money for whatever reason and that you aren't just doing this out of greed. Keep devving homebrew games!

Eh, fair enough. Sorry if that comment ended up being a bit rude...

Why is this a paid game? You do know that you don't own any of these properties, right? (No offense but you could get sued for stuff like this)

Will this ever be ported to the NES?

The Game Boy version of this game also has a set (I know that you are already aware of this but this is so you can add it to the main body of the page):
https://retroachievements.org/game/21929

Will there ever be a download for this game?

The RetroAchievements set has been updated to have cheevos for the new levels, so the latest version is now the one supported instead of the old one, which has been marked for RA.

Any plans for an N64 version?

This is just next-level preservation, dude, keep going! Oh and add Game & Watch Collection 2 and maybe if it's possible add the DSiWare versions of some G&W games.

The games that were rereleased are: Ball, Chef, Donkey Kong Jr., Flagman, Helmet, Judge, Manhole, Mario's Cement Factory and Vermin. Sorry if that's too much for you 😅