Copper cures ich and velvet.
While in copper you can treat for flukes and internal parasites with General cure, metro or prazi pro.
General cure has a bit of both in it so it's used more often.
Once done with treatment you need to have a sterile tank to transfer the fish to.
All tanks need to have their own equipment and not used together.
There are also other methods such as TTM (tank transfer method which cures ich and does not involve meds. You can also treat for flukes while using TTM.