Easiest: THe Final Boss In FF X-2. I just kept dishing out the pain and the white mage heals! I expected so much more. Although the story had me captivated too much to bother! And Final boss of Resistance 2-all you had to do was shoot the stupid orbs!!!
Hardest: the final boss in new PoP where you have to evade it's attacks and just crawl around and activate the plates. You had to do one part EXACTLY like they developed it. Although the beforehand swordfight and final finishing combo were AWSOME!
He is (almost) impossible to beat >. Before I can get his health a color down he'll kill me, so I'll say he's the hardest boss.
The easiest boss for me would be fighting the Rock Titan in the Hades Cup in Kingdom Hearts 1. All you have to do is hit his feet till he falls, then climb up to his head and whack him till he dies. :/
Final fantasy: easiest: Gerogero and abadon from ff8. one phoenix down and they die ^^ Hardest: i'd have to say ruby/emerald weapon from ff7, that is until you source farm.