(I'm using their Tenrou Island versions since that's where we saw most of Bluenote's feats... and also because I personally hate the Avatar and Alvalez arcs!)
Bluenote wins mid-high diff
While Laxus' strength and speed would be enough to stand and fight, his moves would still be very crippled by Bluenote's gravity (for instance, if he uses a roar, the torrent of lightnings would fall on the ground). The main reason Laxus would still give Bluenote a good fight is his lightning speed, even crippled by huge gravity, it should still be better than Bluenote's speed and maybe even enough to dodge his Black Hole. But for the rest, Bluenote's fists should rival Laxus' crippled electric punches, and Laxus would use a lot of magic to make his attacks land on Bluenote, so he'd run out of magic long before him.
