Warioland 4 is amazing, and definitely one of Nintendo's greatest achievement. I didn't appreciate the weirdness as much as a kid, but going back to it, I simply love how off the wall it goes, and how it is halfway a Mario platformer and halfway a sonic game due to you having to rush back through the stages. If you have ever played Pizza Tower, this is the game that inspired it.

Speaking a Wario, the Warioware games were some of my favorite pick up and play titles. There is just so much to do, even after you finish the short campaign. The DS one is by far the best one though.

Dragon Ball Z Legacy of Goku 2 and Buu's Fury are some of the best Dragon Ball games period, and are pretty decent RPGs in their own right as well. I more or less experienced the entire story of Dragonball Z through those games, and they do a fairly decent job of retelling the events (Aside from the first Legacy of Goku game, which is garbage.) If nothing else, give the music a listen. Not only are their some good remixes of the American DBZ soundtrack, but a lot of original songs that are masterpieces.

I may add more if I think of any