Once a player reaches level 10, he can create a supergroup. To do so, he must go to Paragon City Hall (AP) or Freedom Court (GC) and register in the building. A supergroup can consist of this one player only. He can then invite additional players.
A supergroup is a persistent group that exists over playsessions without the need to being invited every time. Though you share a group with others, you are not teamed with them! A team has to be created independently from the group. Members of different supergroups can still team up.

The advantages of a supergroup is the group member list, which can be seen as additional friend list. It is also helpful for leaders to see when the members last played. The supergroup channel helps organizing and keeping contact with the other members. In addition you have the supergroup mode to identify yourself as part of the group. EXP are not shared between group members when not teamed. Each group also has the possibility to deposit enhancements in a vault.

When you register your supergroup, you will have several choices:
-Name of the group
-Motto of the group
-Names of the 3 ranks
-Group emblem
-Group colors
-M.O.T.D.

As it is at the moment, only the hero who registers the team has to be lv10. There is no level requirement for joining members. This might be changed in the near future though, requiring heroes to be lv10 to join a group.

Supergroup Name
This is of course the name of the group. This is also the name that will appear below player names, indicating them as part of the group once invited.

Group Motto
This can be any phrase, like "For justice!". So far, I think only group members can see it.

Rank Names
Every group has 3 ranks:
Leader, lieutenant and member. This titles can be renamed. Leaders can promote and demote other members, but cannot demote other leaders. I don't know yet what the different rights are.

Group Emblem
When registering a group, a group logo/emblem can be chosen. The default one is the anarchy A. This emblem is shown on the group sheet and also replaces a player's regular emblem when in supergroup mode.

Group Colors & Supergroup Mode
2 Colors can be chosen from the regular color menu when a group gets created. Every member can then go to the costume menu (supergroup tab in chat window, settings) and individually decide on where to put the group colors. Meaning, a list of all costume parts is shown with each the primary and secondary, regular colors. Nest to them are the 2 team colors. A player can now switch every single regular color for one of the group colors. The costume itself never changes (except for the emblem).

Once the colors have been decided on, this gets saved a the supergroup costume. Players can switch between their regular costume and the supergroup costume by clicking the "Enter/Exit Supergroup Mode" button in the supergroup tab.

M.O.T.D.
"Message of the Day". Leaders can enter a new MOTD anytime on their group sheets. Group members can have a look at the MOTD by clicking the "MOTD" button in their supergroup tab.

Supergroup Channel
Players can change to their supergroup channel by clicking the S on their chat window or using the /sg command. All online group members will receive messages sent in the group channel.

The Supergroup Tab
On the chat UI (default in left-bottom corner) there's a menu at the top, which reads "Team Friends Super Email Options". Click on Super to access the supergroup tab. Here you'll see the group's name, the motto, all members, their ranks and when they logged in the last time.
You can also access the group sheet and costume menu by clicking the "Settings" tab or have a look at the MOTD.

The Supergroup Vault
Inside the Paragon City Hall and Freedom Court buildings there's a supergroup vault. Group members will be able to deposit enhancements (and inspirations?) for other group members. This is the temporary vault solution until HQs get implemented.

Group Vaults are not working currently!

Additional Info
So far the group colors and emblem can not be changed after registering the supergroup. This might or might not be intended.

Initial Set Up of Character's Supergroup Colors:

1) In the chat panel (c), click the "Super" button.

2) In the supergroup panel, click the "Settings" button.

3) In the settings panel, you'll see a brief description of the Supergroup and the two colors you will be working with. Press the "Accept" button.

4) In the next panel, you'll see your character and a variety of primary and secondary colors. The first colors shown will be the colors that you ordinarily use. The second set of colors will show your Supergroup colors. Pick and choose among the colors available those you'd like to see on your character. You have a primary and secondary color to chose from in each section. Press the "Accept" button when you are done chosing.

5) Go back to the supergroup panel, press "Enter Supergroup Mode" to use your supergroup costume.

Note: You can change your color choices at any time but following the above steps again.

Changing into and out of Supergroup colors (post set up)

1) In the chat panel (c), click the "Super" button.

2) In the supergroup panel, press "Enter Supergroup Mode". Your character will now show off the supergroup costume you created earlier.

3) In the chat panel (c), click the "Super" button.

4) In the supergroup panel, press "Exit Supergroup Mode" to change back into your original costume.

/sg
Send message to super group channel

/sg_accept
Receives a supergroup accept

/sg_decline
Receives a supergroup decline

/sgcreate
Start a supergroup

/sgi
Invite player to join supergroup

/sginvite
Invite player to join supergroup

/sgk
Kick player from join supergroup

/sgkick
Kick player from join supergroup

/sgleave
Leave your current supergroup

/sgsetcostume
Sets supergroup costume parameters
(Exact parameters unknown)

/sgsetmotd
Sets supergroup "Message of the Day"

/sgsetmotto
Sets supergroup motto

/sgstats
Display supergroup info in chat window

/promote
Promote supergroup member one rank

/demote
Demote supergroup member one rank