I had the same problem wasn't until 4 years before till I actually beat it. I hated Wario's Castle. IT was a Pain
Loved that castle.
I still have this game and every now and again ill throw it in the Ol' Grey GB and play it through completely. Doesnt take all that long, and ive mastered it. Thats what you get when you give a young kid a gameboy and 1 game...Lol.