DrinkyCrow
2003
The biggest positive is that Pokemon Colosseum forces you to use Pokemon you wouldn't consider otherwise and this can lead to some interesting strategies and generally forces you to learn how to game Pokemon's systems (i.e. get good). The strange grimy atmosphere the game establishes is a great change from your typical Pokemon game. On the other hand, aside from following the story from point a to point b, there isn't a whole lot to do. It makes Pokemon Colosseum feel like a proof of concept for the subsequent Pokemon XD.
I like how the Colosseum spin offs force you to use Pokemon you maybe wouldn't consider otherwise. This one has better distribution of Pokemon and some post-story content that makes it feel ever so slightly more well rounded than the first Colosseum.
Excellent Fire Emblem if you're in it for gameplay. Yeah, killing your guys is antithetical to the characterization of Marth but it makes for some interesting emergent storytelling. As Kaga intended.
Working backwards through From Soft's catalogue; it's really interesting to see the earlier versions of ideas iterated upon in later From Software games. Also just a solid dungeon crawler borrowing elements from other adventure games like The Legend of Zelda.