Do you want to tweak a little or a lot? In the Roster Editor (Main Menu > Settings > Rosters) you can edit almost everything about your teams. There are some key points to note:
To start a Dynasty, there must me a specific amount of GOLD, SILVER, and BRONZE players. You can't create a team of all GOLD players, sorry :).
GOLD and SILVER players can start with up to 3 Skills
Only GOLD coaches have 2 Scheme options
Team STRENGTH ratings impact how the CPU utilizes it's players based on selected difficulty
Have fun and share with the community what you come up with!
Go to the game's community page and search the Custom Rosters pinned discussion.
https://steamcommunity.com/app/4796920/discussions/0/664989359334816000/