The rest of these will be in no specific order, but I'll number them just cause I like to.
2. Battle with Legendary Pokemon / Battle with Elite Four, EL.
The intro is all I have to say about this. The intro ALONE makes this song into one of my favourite tracks in the game. It's slow, suspenseful and builds up an absolutely gruelling fight. You're facing an ELITE FOUR MEMBER who's Ditto transformed into a copy of GOD. There's no other track as fitting for this battle as this one. The intro has you coming to terms with the fact that this is happening before you're tossed right into the heat of the fight with a fake idol of a God.
3. Atmosphere: Tourmaline.
Mt Pyre remix. Give. GIVE. GIIIIIVE. Aside from my blatant fanboying over this one track, it's honestly a masterpiece and fits the expansive and dreaded Tourmaline Desert fairly well, despite the fact that we can only hear it in jukebox in the Pokegear, but it has me pumped to go there and see what awaits us. Give Corey's Crobat pls.
4. Battle - Countdown. Sigmund's overworld track.
The track that plays when you encounter Sigmund for the first time and honestly, it sets the scene down perfectly. It's ominous, dark and full of all kinds of foreboding feelings. It feels like something isn't right, and honestly, there isn't. There's something fishy about him, and you soon find out what it is. It's a slowed down version of his battle theme, which if you choose to fight him in Yureyu, fits him and the situation PERFECTLY. You're fighting in an abandoned building, full of old electrical appliances against an expert of the electric type. Glorious. It's also a remix of Colress' theme and Colress is epic.
5. Reverse Gym / Battle with Entity Shade.
I like this track.
I like this track a LOT.
Where to start. It's ominous, starts off eerily, fitting for a gym leader of the spookiest type. It carries some of the electrical feeling you get from the track that plays in the factory, but amplifies it, now it sounds fitting, where before it was shockingly out of place. Something that's rather weird for an abandoned Power Plant. You'd imagine it'd be more like the FRLG Power Plant but it isn't. Instead it's quiet, ominous and you feel like something VERY bad is about to happen at all times. Not only that, but when you realize that the track is the reverse of the actual Gym Leader track it sounds all the more ominous. Like Mono, I find Shade to be the Disc 1 Final Boss of Reborn.
Just a jumbled up grouping of all my thought in a semi-coherent list, I guess.