The only thing to fear, is fear itself.

DK/Rets don't have much fear protection on their team.
That is basically their only big weakness.

Aside from that, they're a tower of strength.
With a lot of cleansing and healing power on the team.
Emergency buttons etc.



Not saying they're the only team which will be viable for battleground/world pvp style play.

Looking at 4x Boomkin + 1x Resto Shaman...
You'll likely need to approximate the Eclipse proc, which will be a huge boost over ignoring it, but fall far short of ignoring it.
Go with strings of Wrath x3/x4, followed by Starfire x3 or so, when single targeting anyone/thing.
You'll have a massive amount of AoE power between Force of Nature, Fire Elemental, Hurricane and Starfall.

I'd be tempted to go with a 2nd or possibly a 3rd shaman.
Staggering the Tremors is stronger fear protection, which is one of the larger weaknesses of a box team.
An Elemental Shaman adds a massive amount to any caster based team.
If you were to go with Elemental (Shaman), Resto (Shaman), Balance Druids x3, that's how I'd probably spec them.
However, if you had three Shaman on the team, I'd spec them all Elemental, and not use the Druids for healing at all, since that drops them out of Moonkin.
Not sure you want to change your team dynamic that far, but I'd really look at an Elemental Shaman on a caster team.

Play what you'll find to be fun, not what others say will be the strongest option.
But realize going in, what your strengths and weaknesses will be.

I'm messing around with both 5x Feral and 4x Affliction + 1x Discipline.
Neither is the DK and 4x Ret, but both are fun.