What exactly is giving you difficulty in pet PvP? It is difficult to give definitive answers without a better description of the problem. You have a very good stable of PvP pets, so you can build some strong teams. There is a very steep learning curve going from the AI controlled tamers to thinking opponents, so be prepared for some real strategy
Some small tidbits:
Switches can make set-ups hard. For example, very few players will let you do something like Howl->SoP. Unless they have some sort of Dodge/Deflection mechanic, they will simply switch a new pet in that doesn't have the Howl debuff. This goes for many types of setups.
You will be facing the same comps a LOT, so begin memorizing the more common patterns and not blowing big CD's if you suspect there is a counter waiting to be used. For example, Trying to gate a DAH on the very first turn as soon as he comes out will likely get you blinded, therefor wasting the long CD on NG.
Save defensive mechanics for obvious setups. For example, a Crow/Raven uses Call Darkness and you are on something with Deflection/Evasion. Use the Deflection on the next round as 99% of the time the crow users will go for Nocturnal Strike. Good players will juke this, but mediocre players smell blood and just go for it.
Make good use of weather switches. Using the crow example from above, a lot of times, players will lead off with the crow/raven for CD/NS. If you have something to change the weather, bring him out first. Because of the Flyer racial, the other player will likely go first. Once again, a smart player will put off CD for 1 turn to see if you are going to switch the weather on him, but usually the crow will lead of with CD, so you can switch the weather right after he does which will negate the advantage of CD for it's heavy-hitter NS.
Learn to disrupt the other player's game-plan. Well timed stuns, gates, dodges, etc. can wreak havoc on the other player, so don't just use them willy-nilly. For instance, when a Kun-Lai Runt user hits you with Frost Shock, you can almost guarantee that he is setting up a Deep Freeze, which results in massive dmg. Either swap your pet, gate, defensive ability, something. Try not to eat that massive hit.
Memorize the racials. Very important knowledge to have. Knowing how the Undead racial works (1 free hit or 2 depending on speed rating) will serve you well, and knowing to do important stuff like swapping in aquatics to soak DoTs, Undead dmg and the like is really key. Also can avoid making one look very silly. I love being on a rabbit and watching someone trying to stun/crystal prison me....
Some players completely rely on broken mechanics and are terrible when they don't work right. For instance, I used to run into a Murk player who used Righteous Inspiration switched into a Bonestorm on his frist turn every single time. After I got him in the queue twice in a row, I switched in a Pandaren Earth Spirit and simply Crystal Prisoned on my first turn, which completely shuts down this setup. When the cd on RI was 1 round from being up, I would rotate the Spirit back in and wait for Murk to come out and try again. I beat him every time I ran into him after that. My point is, some people are just bad pvp's with really good/broken pets, so it can be worth it to stick around for what looks like a hopeless fight, or if you keep running into the same player, to adjust your group to counter him. The other side of this coin are good players with good/broken pets. These types of players require very specific counters and strong tactics (along with a little luck) to have a prayer against.
There are tons of other things, but I will let other posters offer their insights