Robots can be assigned to your 4 sky teams. They are added to a team and removed from a team just like Gumballs are added and removed. The only difference is that any given robot can be assigned to any of the 4 teams and can even be part of multiple teams at the same time.
Reminder: the number of places in each team is limited by your Leadership score, using many robots will therefore reduce the number of gumballs you can use and vice-versa.
When you enter Space for the first time, you might be unable to use robots in your Space fleets.
Use of Robots in space is unlocked by the Mechanical Combat Troopsresearch that you can find in the Robots tab of your Tech Hall.
You'll be able to use a limited amount of robots in each fleet. This amount is defined (mostly/entirely ?) by your research. With only Mechanical Combat Troops at level I, you can use 4 robots in each fleet.
Each robot can be assigned to any of the 4 fleets but to only one space fleet at a time. Unlike Clones, they can be freely removed from a fleet and reassigned to another one or kept in reserve.
Robots assigned to a Space fleet can still be assigned to one or more Sky team(s).
Additions to and removals from Space fleets can only be done when the fleet is idle.
Robots are quite a valuable asset in space since 100% of the assigned Robots' energy is added to the fleet whereas only a fraction of your Gumballs' energy is added (likely only 10% of it when you start Space exploration).