It's the theme that plays at 1:00 of the video

I looked all over playlists for black/white and hgss but I couldn't find it. I know it's gen 4 or 5

That doesn't sound like Gen 4 or 5 to me. If anything it sounds like a post game boss fight. Possibly against a character from Gen 4 or 5 but I don't recognize that tune from that era at all. This video looks to have been made after Gen 5 as well

Wait. Is it a remix of the Cynthia theme? She is the only character I can think of powerful enough to warrant that song:

Edit: hell nah this ain't it

The drums in the back and the sparkle sounds definitely sound gen 4 to me but I'll check out x/y soundtracks the guitar reminds me of the elite 4 music

No it's an official song i remember playing it in a game

search concluded. It was N's battle theme

our work here is done

Oh wow. Good s***! I love N, too.

Thanks for the help bro