Anyone know any decks that can counter or at least do well against mono-blue devotion/master of waves deck? Faced one and couldn't do much against it with my selesnya deck.

That's because Selesnya is ill prepared to deal with the threats it presents care of green's overwhelming lack of removal. That being said, the Mono-Blue Devotion deck is a glass cannon. If you can take out Master of Waves and Thassa (or at least keep her from being a creature), then it's a breeze. But just off the top of my head, in G/W you have access to Selesnya Charm for Thassa, Fade into Antiquity/Sundering Growth for Bident of Thassa, and both Gideon, Champion of Justice and Banisher Priest for Master of Waves. In addition you could easily have some fight spells in the SB or even just where something as simple as Unflinching Courage will make the race unwinnable for them (care of lifelink).

To be honest, I would worry more about how to counter Mono-Black Devotion, as it poses some REAL threats with its versatility (I can say that for a fact from taking a version and doing very well at Theros Gameday - including beating Mono-Blue Devotion). But even then, a fast enough start should propel you to victory.