You can play Metroid II on a GBC, GBA, or SP... and I can't remember about Micro.  I bought my copy for about $15 (Player's Choice edition) in late 1998, because the GB Color was my first handheld system.  Technologically, it is a remarkable feat.  It's also an interesting "missing link" between Metroid and Super Metroid.
Although I respect Super Ghouls 'n Ghosts, it is not a game I want to play again.  I'm also not keen to pay $8 for a game in which I probably can't beat the first level.