Well I'd recommend ensuring that any healing you do there is maximized by the bonuses from your leaders. Temp HP are your friend (I like warlords for this, but clerics are better healers). You're level 6...hmmm... nothing super broken that I can think of (now that RROT has been nerfed).
I'd recommend a defender who mitigates damage (shielding swordmage) as even if they ignore your mark, they still do a bunch less damage. (IMO)
For strikers, Rangers are probably the most damaging types...I like Avengers myself, especially if you go with the Master of Defense option (look on the Wiz, CO boards).
Leaders - as said before, I'd suggest either warlord for their temp hp powers, or Cleric to get the most hp out of your HS's.
If I was putting a team together, I'd probably do 2 defenders, 2 strikers, 1 leader. Most likely, Goliath ES Warden (for pure toughness) or DB fighter (multi-marking/minion destroyer), Eladrin Swordmage (shielding), Elven Ranger (two-weapon fighting (for bonus feat) but using bow, Human Avenger (Master of Defense), and either DB Inspiring Warlord
or Elven/dwarven ranged Cleric
Oh: Just thought of something that seems to be a minor bit abusive (bugbears still use oversized weapons when most other races have had them nerfed, so brutal rogues work well.) Not sure if the Hybrid rules will be loaded in the CB by then, but you might be able to get a pretty crazy combo with that as well...
