Wow, I have a list of these^^
Okay, so from OoT, I liked Bongo Bongo and Twinrova.
From TP, I liked Fyrus, Stallord, and Zant.
In Paper Mario, I liked Huff N. Puff and General Guy.
In The Thousand Year Door, Macho Grubba, Cortez, Doopliss, Gloomtail, Shadow Queen, and Bonetail.
And in Starfox Adventures, I liked Galdon, RedEye King, and Drakor.
I tend to like bosses that actually give me a challenge, or bosses that are fun.
When I have a boss battle, I want to have barely any life left when I finally kill them, and I want the battle to be EPIC.
If I have to be revived a few times, first, that's fine, too^^
But the easy battles just get too boring D: