Practice multiple classes
I can almost guarantee that teams like Pandemic and MoB Gaming will have multiple teams in the top tier just so they can meta game another top team that's in the same range for points.

Since WSVG's fall, most of the members of Pandemic have been practicing multiple classes. Their paladin Sck has learned Warlock and Druid, Ecilam is also learning a warlock and rogue, and Kintt has already proven himself in tournament play to be able to play multiple classes at the top level as well. I'm sure the rest of their teammates are all just as well-rounded too.

MoB Gaming is rumored to have a team lined up of Ohnoes(mage), Zecks(rogue), and Swarm(priest). Swarm(aka Fershie) originally was a mage at 60 and plays druid/paladin also exceptionally well. Ohnoes is also very skilled at rogue, making their team very versatile even if Zecks doesn't have to play anything else but his rogue.

The skill cap of WoW isn't very high, so learning new classes shouldn't take very long if you've been seasoned in top-tier arena play.

Find a talented Rogue and Druid
Almost every top 3v3 team on Bloodlust(BG9) involves a rogue and a druid. Both can be used effectively in many different lineups, and most likely the top tier teams will have both in their lineup.

Right now on Bloodlust, the top teams are based around teams that can farm RMP(Rogue, Mage, Priest) teams because of the composition's popularity. Most of those teams involve a rogue/druid centric team, mostly double rogue/druid or warrior/rogue/druid.

Make one team that will be able to counter RMP
RMP is still the most popular 3v3 matrix by far, being that it's the only composition mages can play in successfully and one of the few comps disc priests can play in as well. Double melee teams are extremely strong against RMP because of the amount of physical damage it can pump out so fast on cloth if both melee are on the same target. Warrior/Rogue/Druid is also a strong counter to any team that runs a Warlock as well, being that both melee can sit on the warlock.

Strong Counter-Comps to RMP:
Hunter/Warlock/Druid
Rogue/Rogue/Druid
Warrior/Rogue/Druid
Warrior/Rogue/Paladin
Warrior/Warlock/Druid

*It's arguable that some of these comps are true counter-comps, like Warrior/Warlock/Druid, but they're definitely at an slight advantage versus that comp depending on how well the druid plays.

Have a second team that will counter "RMP Counter-Teams"
Since RMP will probably be the most popular lineup ran on the event realm, like stated previously that an abundance of RMP Counter-Teams will probably be in the top tier. The most popular comp in the top 20 of the bloodlust 3v3 ladder is Warrior/Rogue/Druid, with Xahlior/Loz/Vorrent's(With Bwrx as a sub-in) "Fight Music Off" being the #1 team in the ladder. They've told me strong teams against their comp are Warrior/Mage/Druid and Warrior/Rogue/Paladin.

Warrior/Double Healer with using Druid/Resto Sham/Paladin would be a strong comp versus it as well(Priests are still too squishy to last versus that comp. But, any team running Warrior/Double Healer doesn't have a good chance of getting to the top tier without using a different comp at the start to farm high.

Be available to play at all hours
Being that Blizzard will probably use a Ladder-Rating System, there are ways of abusing it. Teams during season 2 on Bloodlust tried to "dodge" other top teams once they got high enough to try to secure the Merciless Gladiator title by playing their 10 games during off-peak hours. Blizzard will require every team to play at least 10 games a week and any team in contention for the top 4 teams will attempt to keep their spot with any means necessary. The "hardcore" teams will have their fridges packed with Mountain Dew and Energy Drinks, take shifts to monitor the ladder, and try to catch every team that's queuing up in the top 20. $75,000 is definitely a respectable amount to be playing for and I guarantee you Team Pandemic will be one of the teams that'll hardcore it.

Overview of Key to Success in the 3v3 Ladder
- Have 2-3 teams in the top tier to meta-game with.
- Be educated in the rock/paper/scissors of 3v3
- Make a RMP Counter-Team
- Find a talented Druid and Rogue
- Have another Counter-RMP Counter-Team
- Practice multiple classes

Good Luck to all teams participating in the future!