re: Best Final Boss Themes

Secret of Mana: Meridian Dance
The final battle against the Mana Beast. I like this one more than some of the others mentioned because it incorporates some of the earlier musical themes from the game and really makes the song feel like part of the story.

Super Castlevania IV: Dracula Battle / Theme of Simon Belmont
The atmosphere of the first track after defeating the sub bosses, walking down the corridor with the torches coming alight, and the first part of the battle with Dracula is good, but it gets great when Simon's Theme kicks in when you start to get the upper hand and Dracula also steps up his attacks.

Arcana: Battle with Rimsala
This theme takes the opening of the main battle theme and then opens up into a much more elaborate track. I'm a big fan of the driving bass of many SNES tracks, and this one delivers there.

Katamari Damacy: Katamari of Love
This game doesn't have a "boss" to beat (other than perhaps your terrible father), but this song serves as both the final level, a race against time, and the ending credits all rolled up into one. Very cathartic after racing to collect every little thing and make an adequate moon.