Minecraft – How to make floating objects

First, you should add the teams that you want as normal:

For the next part you will need something to edit the NBT data of the world, such as NBTExplorer.

Navigate to your world, and inside that, open data > scoreboard.dat > data > Teams.

Now you should see some 7 entries, these are your teams that you created. You can open them up and check the Names inside to see which is which.

You should see that one of the tags each team has is a Prefix and a Suffix. From here you simply need to double click on the Prefix/Suffix you want to change, and enter the string that you it want to show up as. You can make it anything, and use Formatting Codes to add colour or effects.

(Note I did 2 s/p for Team_1 and 1 s/p for Team_2)

Once you've changed what you want and saved, these should show up as the prefix and suffix of the teams in game.

You can use a named invisible WitherSkull.

summon WitherSkull ~ ~ ~ {
    CustomName:"Whatever",
    CustomNameVisible:true,
    Direction:[]
}

(This is from memory, but I think that's it)