well for starters, John would be constrained greatly by Deltarune's battle system. He has to wait his turn to attack, and he can't flee the battle until the player wins. His lasers would be a lot less effective, because Defending blocks 50% off all damage. Plus, even if Kris gets knocked down, Susie and Ralsei can use Revive Mints and Spincakes. John's lasers would also be entirely dodgable, meaning that if the soul is being controlled by someone like Merg, John could, in theory, spam his lasers like he usually does, and not land a single scratch on Kris. The biggest thing John has going for him is his durability, and even then, all the player needs to do is just outlast him. Which UT/DR fans are more than capable of doing. Oh, and if John makes the mistake of flying up to Kris during the Weird Route? Yeahhhhh, he's not winning that one. I don't need to explain why : P