To put it simply, Asgore's story is the same as Asgore's Story in Undertale.
Asgore in battle is very different from his Undertale counterpart. He absorbed the six souls after Sans warned him about the 7th human after seeing them kill the entirety of Snowdin. He is not only now an god-like creature, but he has gained an IRIS. An IRIS deflects all damage, after 12 turns, the IRIS will go down, letting the damage be done to Asgore, and he will go down in 4 hits, even though the IRIS is only down for 5 seconds. Once he is down to 0 health, the text "But it refused." will appear then the game will skip to the "Real Fight" And you are thrust into a cross between Asriel Dreemurr and the fight they just fought. After Asgore is killed a second time, the game goes to a Genocide Ending (Due to the story being true to Original undertale's story until the monsters are locked away, it is the same as a Undertale genocide ending.)
- The name of Asgore's shield may be a reference to Overwatch, as one of the characters (Specifically Zenyatta) in Overwatch has attacks that rely on the Iris.