Good mod, but you should include another links besides MEGA because the file is largest than the free download limit.
About the songs itself:
In my opinion, using the Pokémon Origins battle themes are better options than Pokémon ORAS battle themes. You can check Pokémon Origin songs here: (some are cover)
Pokémon Origins - All Musics.
In special, any battle song from Origins is very better than the song you chosen from ORAS (in my opinion).
About making some songs play only on certain conditions I totally agree, some examples are:
Main Screen Theme - It plays while the player is still not logged-in: https://www.youtube.com/watch?v=Dd52jjeukpM
Bycicle Theme - It plays when the player gets in a bike: https://www.youtube.com/watch?v=yBgNEJNlb3I
Gyn Leader Battle Winner - It plays when there's only 1 Pokémon remaining from the gyn leader: https://www.youtube.com/watch?v=5ZuTcK51FEQ
Gyn Leader Battle Loser - It plays when there's only 1 Pokémon remaining from the player: https://www.youtube.com/watch?v=MSnu5sjCfqM
Pokémon trainer battle - It plays on a trainer battle only: https://www.youtube.com/watch?v=ZU1HEDuultc
Pokémon horde battle - It plays on a horde pokémon battle only (3 or more pokémons appears at the same time): https://www.youtube.com/watch?v=8G5HIJkkxU0
Rival's Encounter Theme - It plays when the rival appears on scene: https://www.youtube.com/watch?v=PLlCFo0wxrE
Champion Battle Theme - It plays on any battle against a champion character: https://www.youtube.com/watch?v=z5s4VYC9xR4