Tower Theme: Monster Hunter - Tbh this whole post could just be filled with a MH soundtrack anthology, but I feel like highlighting this one because it manages to create a sense of tension and enormous scale in a game series that bombards you with it nonstop. Every small detail from the airy background noise creating the sense of size, the high pitched howling and whistles that add that spice of mystical tension, on top of deliciously simple but powerful percussion and strings. Also everyone needs a bit of HOO HAH in their lives (which Sakurai seemed to forget when he annihilated Diddy Kong). Just a little bit of everything nice without going overboard, truly makes you feel like the battle is something different from your usual hunts.
Cipher Admin Battle: Pokémon Colosseum - This game easily has some of my favourite tracks in the series, and this one is such a great boss battle theme because of how it takes its time to build up the tension, even with a false start. Knowing that fighting a full team of pokémon would take time with all the animations etc, they took advantage to really build that sense of tension into a sudden explosion of energy.
I get kinda carried away talking about videogame music, but I really can't help it.