You can upgrade and evolve your players by committing them to an Evolution slot and completing gameplay challenges with that player. Once you complete the challenges, that player will have permanent upgrades.
Each Evolution comes with a set of levels of challenges for you to complete. They can range from simple, ‘Play 5 Games where you score with this player in your starting XI’ to challenging ‘Win 10 Ultimate Team Champs matches with this player’. Complete all of the challenges in a level to earn the upgrades, and unlock more levels of challenges to complete.
In-progress Evolution players cannot be submitted in SBCs. However, once the Player Item is fully upgraded and the Evolution is completed then you can use them in SBCs.