My two favorite final boss fights?
Well, these two would fit the bill;
Zack and Wiki Final Boss: Barbaros and Giagoros
Typical Barbaros, always have something up your sleeve don't you? Well, I never expected Z&W to get this EPIC! A huge, hulking, mecha crocodile! Well played, Barbaros.
The music just adds to the effect, wow, just wow. And the ending, so epic and bittersweet, but it all turns out well in the epilogue. Or should I say EPIClogue
Another favorite would be Epic Mickey's Final boss; The Phantom Blot. Not to be confused with it's lesser minion, the Shadow Blot, who technically IS the final boss as the Phantom Blot is not fought directly. I was running through the Blot's innards, painting every enemy in sight, it was soooo epic! When I got to the last bloticle, I looked at my mom (who watched me play almost the entire game btw) and said "This is it. I've been as much of a Hero as I could be, let's see it it pays off." Well it did. After I popped the last bloticle, we were rewarded with the best possible ending the game had to offer. It was breathtaking! Go Oswald (and Gus) you rock!