Okay so you all know that round 1 took place with the Mane 6, so I've been doing some research into what other groups of six can be used. So lets begin.

Mane 6 - So this should be obvious unless you've just joined the fandom or you live under a rock, they are as follows..

Twilight Sparkle
Fluttershy
Pinkie Pie
Applejack
Rainbow Dash
Rarity

Background 6 - The much loved background characters

Derpy
Time Turner/Doctor Whooves
Lyra
Bon Bon
Octavia
Vinyl Scratch

Reflections 6 - The Elements of Harmony in the Reflections arc of the MLP comics

Trixie
Derpy
Queen Chrysalis
Flim
Flam
6th is unknown

Manehattten Six - Based on the fanfiction group, the stories are set where Twilight Sparkle heads to Manehatten rather than Ponyville.

Twilight Sparkle
Daring Do/Honey Do
Blossomforth
Orange Sherbet - may be excluded for age
Octavia
Trixie

Anti Mane 6

Antagonist six-

Trixie
Flim
Flam
Gilda
Lightening Dust
Sunset Shimmer.

Musically themed

Fiddlesticks
Octavia
Vinyl Scratch
Beauty Brass
Frederic Horseshoepin (or whatever it is)
Lyra Heartstrings

I'm open to more suggestions based on fanon or themed groups

Ah'm a little surprised ta see the Manehattan Six on there. Ah'm far from the first or best to start an alternate Elements universe, woulda thought surely the Cadanceverse would be used before mine, or the Lunaverse, bein' as it's directly or indirectly the inspiration for a lot of 'em.

Still, looks like a fascinatin' operation. An' by the way, ah agree with not usin' Orange Sherbet in a ship. It'd be... weird. For a number of reasons.