Board Thread:General Discussion/@comment-28737464-20170223120526/@comment-28662609-20180204191348

Ignoring Mettaton NEO (because it is obviously just one attack), I'll say Papyrus, because you can get past after 3 attempts and it isn't hard anyway, also very easy to spare or kill. Toriel may stop attacking after 2 HP, but you risk death to actually find this out and you just use all your heals. Mad Dummy is annoying first time because you have no idea how to get past. Undyne is really tricky first time and how you just figure out how to spare her is beyond me. Muffet is also difficult first try, and also can't be past by just using heals in the right places. Mettaton is quite lengthy to try and spare if you don't know how to or are bad at dodging the bullets. Asgore is really easy, but it is one of the harder ones to no hit. Flowey just seems impossible the first few times it is played, afterwards it is easy, the only thing you have to worry about is missing an act button. Asriel can get incredibly difficult because it just loops and you die in the same place over and over again. Undyne the Undying is the hardest boss in the game in my opinion by far, how anyone can get past it without fully knowing all the attacks is beyond me. Sans is still quite difficult though, but not as hard as Undyne the Undying.

I have done a full 2x speed deathless Genocide and am working on no hit Sans 1.5x speed so I'm definitely one of the better players of this game, and started one of the worst, so I have quite a bit of experience.