Beating Castlevania 3 is one of my highlights of hard as fuck games I beat.....when I was 8 years old. Now when I try it sends me packing. The game is hard. Unfair, silly hard. The Japanese version (while having superior music) is quite a bit easier, I think. Out of everything there, it's Castlevania and Castlevania 3 that may make you think twice about this challenge (unless you've already beaten, if so, kudos).
You're missing the OG Gameboy Castlevanias there. They're not the best of the series, but they're solid games with Belmont's Revenge having one of the best soundtracks, not only of the Gameboy, but of games in general.