Oh sorry I kind of forgot about this!
Any way lets get to the point, even if you've already started the chapter
Flowey would most likely play along with Y/N mocking them continuously before pushing them down and ruining their plans and mock them about it. Or maybe pretend that their plan worked and pout about it before pushing them down and tease them about how close they where, at some point Y/N will stand up to Flowey and Flowey will immediately defeat them, or take their sweet time teasing them. Sooner or later Y/N will play along and finally set a plan to avoid this, and maybe defeat Flowey for a short while, but no doubt he will come back until you permanently get rid of him.
Just some tips about Flowey and WOW that is way too long
