All the talk about Evil Gaia made me think of another one: Dark Gaia's second form in Terranigma. It doesn't take any skill to beat him, you just have to have high enough experience. The first time I fought him I was on lvl. 28, I think, and my attacks only took away 1 HP. It was pretty easy to figure out how to defend against his attacks, but he eventually beat me through attrition due to the pathetic amount of damage I was doing. So I raised my level a few times, and the second time I fought him I was doing 40-50 damage per attack. There wasn't any challenge at all. They should have made it possible to do a reasonable amount of damage to him at lower levels, maybe about 15 points per attack...then there'd at least be some skill involved. I don't think adventure games should be about building levels.

Addendum: Dark Gaia's main attack can't be dodged, you can block it but it still does some damage.