I'm glad it went well for you.
Bone Serpent and Mechanical Pandaren Dragonling are two of the most overpowered pets in the game, so I was fairly confident you wouldn't do badly.
With the typical two-AoE Graves, you want to take him out FAST, before he can get his second round of AoEs off. Even so, he will do a lot of damage before he goes down. I find the Consume Corpse Graves more dangerous, but thankfully it's harder to play, so fewer people do. He's another of the most overpowered - I would say the most overpowered, though I know some disagree - pets in the game. Happily, he's getting something of a nerf in Legion.
Even so, I wouldn't be afraid of Graves on his own when playing that team. Graves will soften you up, but it's his posse that will come in for the kill.
More important, though, is knowing the pets your opponent is playing, and guessing how they plan to use them. A match can be decided based on the two players guessing what their opponent will do and selecting which pet to go first, and that comes with experience.
You could also go into the queue with any set of The Evil Undead that you have - Bone Serpent, Weebomination (with Consume Corpse to gain health after another pet dies), Fossilized Hatchling - and simply bludgeon your way through, using the extra rounds from the Undead racial.
I'm looking through your pets to find more interesting teams. Discodoggy's Tier List http://pvppetbattles.com/2014/12/22/top-high-tier-list/
will give you some ideas for pets to collect and level, and his WoD Teamshttp://pvppetbattles.com/wod-teams/
some ideas for teams to aim for.
Some pets you just have yet to collect. Other pets you do have, but their Breeds are not ideal for PvP. For example:
I'll note that your Fiendish Imp, which you have favourited, is not an S/S breed. If your aim is to level him for PvP, I'd hunt for an S/S instead. Speed is critical for the Imp.
A Junglebeak is a powerful nuke, with Rain Dance providing a quick heal and buff, followed by Nocturnal Strike, which has a 100% chance to hit while the buff is still up, and then Peck to get the most from the buff. Yours is a B/B breed. It's still usable, but the P/P breed would deliver both a bigger heal and a bigger nuke.