Kingdom Hearts II
During the first phase of the battle, Sark's only attack is to fling his disk at Sora, which can easily be reflected with the Reaction Commands "Zone Guard" and "Disc Strike". He can also teleport, but his health is very low.
During the battle with the MCP, Sark's size increases dramatically. He again throws his disk (which has also increased in size) and shocks the ground when Sora is close. Sark's legs must be damaged to make him kneel, so his head can be attacked. Destroying the head stuns Sark for some time, but he will be regenerated by the MCP after a period of time.
After the MCP has had a significant amount of its HP drained, Sark will start to raise a wall whenever Sora attempts to flee. This allows Sora to use the Reaction Commands "High Climb" and "Needle Dive". This will knock Sark out in one blow, making it easier to harm the MCP.
Notes and references