If you played Frontline Commando 2 you might have noticed it is a freemium game, meaning not everything is provided for you and it has lots of micro transactions. The develpors do this to make money of of exlcuisve items and gear usally in exchange for real currency so although it might not be possible for you to get all the squadmates without opening up your wallet their is a way to get more. To start the developers put in difficult challenges in order to obtain extra squatmates but their a ridiculously simple method on how to complete challenges easier.

  1. Get some teamates usually awarded in earlier levels
  2. Don't upgrade all of them
  3. Form a main squad where you upgrade and improve and a basic squad where you rarely upgrade
  4. When using the basic squad do NOT upgrade them and equip them make sure they are the weakest soldiers
  5. Get the required weapon and go ham on the challenge
  6. Due to the squad being poorly trained they will not get lot of kills letting you easily complete it
  7. Make sure you have the required soldier if a challenge says get a drone kill don't use a full squad of snipers
  8. Use this method to gain more soldiers from challenges