Spamton NEO can be fought if Kris meets him at his shop at trash town and accepts his deal: Buy the KeyGen from him, unlock the basement into Queen's Mansion, retrieve the Empty Disk from the machine in the basement, transfer Spamton into the Empty Disk and then place the Loaded Disk back into the machine. This will cause him to transform into NEO, much to his delight, but he will be horrified that his new body is literally held up by strings. He will then attempt to steal Kris' SOUL, before Ralsei and Susie intervene to save them. Spamton can be defeated by fighting, which will result in him trying and failing to transform in Spamton EX, or by cutting all of his stings.

Alternatively, Spamton can replace Queen as the final boss of Deltarune Chapter 2 in The Snowgrave Route. In order to encounter him in this way, you must travel an alternative route after Noelle Holiday temporarily joins your party. You must then defeat every single enemy in the area using Noelle's IceShock Spell. After all the enemies have been frozen, you must steal the FreezeRing from Addison and purchase the Thorn Ring from Spamton for 1997 Dark Dollars. Then, you must fight Berdly and kill him with the eponymous Snowgrave Spell. This unlocks an shortcut into Queen's Mansion via the sewers. When you get into the Mansion, you will find that it has been taken over by Spamton, who has filled it wit Pipis to trap the player. After skipping numerous cutscenes and Queen's Boss Battle you must Fight Spamton NEO as the final boss, by yourself, and with no option to ACT until the very end. Towards the very end of the battle when his health is low, Spamton NEO will boost his defense until he basically becomes invincible but weakens his offensive ability to a fraction of its power. Kris will be given the option to act, where he will have the option to try and call for Ralsei and Susie. Kris must try to call for both of them twice before resorting to calling for Noelle, who immediately appears and instantly defeats Spamton using Snowgrace.