Playing Octave Guitar Licks
You know the style "A Day to Remember" play in a lot, with one guitar playing octaves and one playing power chords on the top 3 strings...., well what notes fit each other, I mean like what octaves fit with what power chords, get me?
Yes , I think I understand your question. If you are talking about playing solo licks in octaves over the power chords, the choice of which octaves to play has to do with the key that the song is in.
The easiest way to determine what you can use is to find the scale that goes with the power chords. Start with a pentatonic minor scale and see which key sounds good with the chords.
Then you can play notes of that scale in octave for your licks for solos and fills.
Hope this is what you meant. If not, please ask again and I will be glad to try to answer.