Top 10 Most Interesting Fights in Undertale
Finally went ahead and watched all the fights. I don't like Undertale too much, but I thought it would be nice to make a list anyway.
Ok so first, shadow, I am sorry to tell you that there is only one Asriel fight. Unless you count Flowey as Asriel of course. Second, if you would have my honest opinion, Asriel's fight is my least favorite final boss fight of Undertale. That being said, he is still a super good boss fight, and lead to an excellent ending. Not to mention that it probably would be the hardest fight in the game if it wasn't for the fact that you can't die.
I'm not talking about his first fight. I'm talking about his second one. Instead of fighting him head-on, you have to save your friends to weaken him. It's an interesting change of pace and it combines everyone abilities (minus Muffet's), making it hard to keep up.
I mean, there is a reason this is at the top. Asriel's fight is one of the best out there

Her ability changes your heart to purple. Instead of being able to move around freely, you have three sections you can be in; top, middle, and bottom. The spiders will let you know what is coming up, so you can prepare.
Aside from having the best video game music of all time, Muffet's fight is overall great. The purple heart mechanic is super cool, and who doesn't like the giant spider muffin?

My second favorite fight after Mettaton EX. I love how Sans is technically the weakest monster in the game, but due to his knowledge he knows how to take out invincibility frames from you, and dodge your attacks. The fact the fight is super hard works here, because you really have to try to reach this fight (not to mention you kind of deserved it). Plus, his attack are super hard to dodge and pretty varied.
I put him above Papyrus because even though they have the same style, you have that whole sequence before he keeps moving your heart around for 5 minutes before he falls asleep. Talk about annoying.
This fight was great and terrible at the same time. No further explanation needed.
I pick sans because yes

My personal favorite boss fight of not only the game, but video games in general. The shooting mechanic makes for crazy unique gameplay, the rating system make it a super interesting fight for the pacifist, and there is a super wide variety of attacks. Plus, it's funny.
For his fight, your heart is yellow. With this color, you gain the ability to shoot projectiles. Not to mention that after you flip the switch, things get real as he turns into Mettaton EX.
When I first saw this... definitely the most interesting.

Undyne's fight is pretty cool. In the pacifist, it is interesting because you need to flee her whenever your heart stop being green, and when you are green you can't move, but can block her projectile. The fight against Undyne the Undying though is basically the same thing but way harder.
Her ability turns your heart green. Instead of being able to move around, you have a shield that you can move with the arrow keys. But that's not all. Occasionally, she will flip your heart back to red.

The blue heart mechanic is super cool and interesting, by turning the game into a platformer. I also like the dilema of this fight. You can just win by losing three time, and than Papyrus will let you pass, but if you do, you wont see his really cool regular attack! Plus, it's Papyrus, and therefore this fight is automatically excellent because of having the best character in the history of gaming in it.
His ability turns your heart blue. While I'm not quite sure what this does, I have an idea. With this, you can really only jump and move as you jump

His attacks are fun to dodge, he is super scary, it's pure chaos, and I love how the objects you may or may not have found in the game are attacking you before those attacks becomes healing items. He can even manipulate your save files.
I haven't seen much about this because he terrifies me. But what I have seen is interesting. All I can say is good luck because you're gonna need it.

This one I mean the first one, the quiz style one. You don't fight him, but you have to be careful of getting wrong answers or you might die.
Just a really fun little quiz.

It's true that in terms of being interesting, it is not the best fight ever, because it uses the basic mechanics, but the fight itself is actually one of the best in the game. His attacks are super well designed, and it's super satisfying to dodge them. I love his trident attack in particular.

Yeah. This fight is very basic. Still pretty fun, but clearly the weakest of the fight listed here. Unless like me you consider Mad Dummy and Napstablook to be boss fights, therefore Napstablook would be lower, but even Mad Dummy is more interesting.
The first boss, so she's obviously last.

