Fireteam Harmony.
The only fireteam of six Guardians allied with the Vanguard. But, the six of them aren't from Earth, or the known galaxy for that matter. They aren't Fallen, Hive, Cabal or even the infamous Vex.

They're Ponies.

The six of them are Guardians, warriors trained to help rebuild and protect humanity. Fireteam Harmony appeared on Earth six years ago. They were fragile, untrained and lost. The Speaker and the Vanguard took them in and trained them. Now they fight alongside every other Guardian, be they Exo, Awoken or just plain old Human, Fireteam Harmony is willing to help.
Their old home has been trying to make contact. It's never truly worked but luckily… Xûr, Agent of The Nine, has found a sign. A single wax seal with the crest of Sun and Moon.

A crossover with Bungie's latest game; Destiny.
I. Own. Nothing.