5. Yu Yevon (FFX) not really a boss battle, as you can't die... Cool music though...
4. Warlord Samurai (Commando 2) If you stand at the right spot, he will never hit you. Also really cool music and the fight to him was pretty tough
3. Minotaur Joe (Dark Cloud). His attacks are so ridiculously easy to dodge and the fight can take really long, unless you have one of the more powerful weapons in the game (gaia hammer, 7th heaven...)
2. Cyber Errol (Jak 3). Probably the worst final boss I've ever seen... All he does is summon dark precursors and use slow laser sweeps...sometimes trying to crush you with the big thing's head...and the weakspot is so obvious...
1. Xeanhort (kingdom hearts 2). I only had slight problems with the second time fighting him at the throne thingy. Also in the final part when you have to rapidly tap triangle to deflect the lasers...just....pointless...
Even without ultima weapon the fight was over so ridiculously fast... Even Luxord took me longer to defeat...