The Canon 600EX-RT flashes have built in radio transmitters in addition to traditional optical wireless transmission. This allows two-way wireless transmission up to 30m, among up to 5 groups with a total of 15 individual Speedlites.

So if you are using these Speedlites you no longer need to buy additional pocket wizards.
How well does it all work?
I don’t have 15  Speedlites  so no idea really… but I did pick up a Yongnuo YN-E3-RT Radio Trigger for Canon 600EX-RTs and test it with three.

And I can confirm that it works with at least 3 Speedlites.

Set the transmitter to Master- I left it on Auto to let it choose the channel
Then as a test, I put each flash in it’s own group.

Use the same Auto channel on each flash, then set each flash to the desired group.

With this all set up the link button should illuminate.

Position your lights and shoot away.
For this quick session I had the two back speedlites at 1/16th power no modifiers. The main light was at roughly 1/8th power, with two grids modifying the light to a smaller pattern.

The Result