There are 90 skills total. Both supportive, defensive and offensive. Each of your ships can only bring two skills to battle along with their primary attack.
All of your five ships are crucial to win the battles.
The Scout | The tiny scout can shield and reposition you fleet.
The Destroyer | A small but powerful missile ship.
The Cruiser | A minelaying medium sized ship.
The Dreadnought | A huge ship with massive torpedo attacks.
The Carrier | The biggest ship with offensive and defensive drones.