Hey giradialkia, as you've told me before, if there's any music help, I can ask you.
Would you like the honor of composing Giovanni's battle theme for DarkViolet? Also, my hack has the 5-DirectSound limit removed (I can now have up to 12 DirectSound samples playing at once), so you don't have to worry about the instrumentation.
EDIT: Also, I forgot to mention, Giovanni will have 2 battle themes in DarkViolet. In DarkViolet, there will be 4 total battles with him, the final of which will take place in Cerulean Cave. The music for the final battle with him should be a more "epic" or "beefed-up" version of his regular battle theme (kind of how in Pokemon Black/White, N's final battle theme is a "beefed-up" version of his regular battle theme). If you want, you can just compose one theme, and I'll do a "beefed-up" rendition of it.
EDIT(again): Also, if you agree to compose his battle theme, do NOT make it a remix of the Team Rocket Grunt battle theme. Remember, Archie & Maxie's battle theme sounded nothing like the Team Magma/Aqua Grunt music, Cyrus's battle theme sounded nothing like the Team Galactic battle music, and Ghetsis's battle theme sounded nothing like the Team Plasma battle music, so I'm asking that if you decide on doing Giovanni's battle theme, it should sound nothing like the Team Rocket battle theme.
Remember, you don't have to do any of this if you don't want to :)