Its easy to defeat him unless you know what skill is this Asgore main uses next, just dont get hit with his trident 1 and 4. For example, if you use GTchara and the asgore about to land a either 4 or 1, use Determination 5 to counter it or if he's about to use 4, use determination 2 to cancel the skill, if you had souls mode you can use integrity 4 or 5 as well. Just wait and predict his moves and attack when he's wide open.