Top 10 Strongest Undertale Characters

Sans is super strong and whoever doesn't see that is very idiotic. Even though he can't with hold your hit. He can doge and he's not stupid. If you get hit your heath will continue to decrease. And note this Chara doesn't do crap unless you finish the Geocide route. In that moment all she is doing is asking for your soul! The animations on Youtube aren't what we are talking about. We are talking about the video game. Sans by far is the strongest.
Sans, in my opinion, is basically the hardest boss to encounter in the game. Before skipping this, I have something to say. Yes, sure, True Pacifist bosses are really strong (Omega Flowey and Asriel Dreemurr, for example), and Chara can basically kill you anytime they want, but in game, Sans is the hardest in all means. In Omega Flowey's fight, you have checkpoints, with the help of the 6 souls. Asriel Dreemurr's fight basically blocks inevitable deaths, meaning you cannot die. Sans' fight doesn't do that. There are no checkpoints/no-death policies in his fight. Although Sans is basically the weakest character in-game (less than Monster Kid), he uses Karmic Retribution (or whatever it's called) and basically poisons you throughout his fight, bringing a bit more stress to the player, even in the menu you're not safe from his attacks, with you still getting KR damage (I'm going off-topic here) which NO other boss fight does. Honestly, I'll keep this brief. Although Chara is the true #1, or the Protagonist, whichever one you perfer, Sans is the boss-fight that kills you (possibly) more than bosses such as Omega or Asriel in-game. Sure, I do agree other bosses have their amazing amounts of strength, such as Flowey almost killing you 1 hit in the beginning before Toriel saves you or Chara in the end of a Genocide run if you decline their offer of the erasing of the world, but in technical terms, my vote goes to Sans.

Chara
can erase the world and to add on, she is a demon in a body, making her twice as strong. This is because she says that she is the demon in the player' soul and she wants to get rid of the world( Earth and the underworld). So all in all, Chars is the strongest character in undertale.
Frisk can defeat all monsters at lv1, & easily defeat them in genocide route. At lv 20, frisk can easily kill Flowey. In fact, Flowey knows he's no match & is so afraid of you that he even knows Omega/photoshop form is no use.
Chara… they overpower Frisk's choice when they say "Do not (erase everything)." Frisk can't even bring everything back if he wants & has to strike a deal with Chara to do so. Even with MAX lv, Chara obliterates frisk with infinite damage & past any defense frisk has. Tis a huge mistake bringing out this kid.
Statistically. Completing a Geno makes Chara the "player" of the game as they take your soul. The player killed Sans and can do again if they want. If Chara=Player then Chara is stronger then Sans but only after a Geno.

Asriel is the child of King Asgore Dreemurr and Queen Toriel, but he seemingly passed away prior to the game's events. His backstory is only focused on in the True Pacifist Route, which means the player does not kill a single character. As a young child, he was a close friend of Chara, a human child who... read more
Overall Asriel Dreemurr is the most powerful character in all of Undertale.
Why you ask? Well let's start of with the fact that Flowey had consumed 6 human souls to become a being of unimaginable power. Now let's add all the monsters in the underground's souls and you have a being that has infinite attack and defense.
Asriel can use every monster in the underground against the player but not to their full extent.
Sure Sans has his gaster blasters and his powerful abilities but the people only consider him to be a hard boss. Sans would be the hardest to fight because Asriel Dreemurr is impossible to destroy.
All and all the Asriel is the most powerful character in Undertale due to having 6 souls and all the monster souls.
Asriel Dreemurr should EASILY be at the top of the list, simply because of all the power he has with those souls. Sure, Sans can dodge almost anything, and Chara and Frisk can completely erase everything, but if you think about it, with all the power that Asriel gets from absorbing every soul in the underground (barring only Frisk's soul, and including all the other human souls, which there are a total of six of), he could easily do either, or even both of those things. Plus, even if he didn't, no matter how many times he gets hit, and who hits him, he doesn't get hurt. So yeah, it peeves me a little that he's in third.

Frisk can be killed and often is killed but Frisk never truly dies, they just come back and try again over, and over. Frisk can RESET EVERYTHING, so Sans stands no chance, Chara can only ERASE the world with Frisk's guidence and Asriel does not seem to have full power over the timeline as if so, why wouldn't he just RESET instantly? He has to kill Frisk over and over to make everyone forget Frisk before he can!
Before someone hates me, this is my opinion and all of the characters above Frisk have their own reasons which are completely valid I am just showing my opinion.
Thanks!
After Chara, Frisk is the strongest. They can respawn & just dodge all monsters attacks. Only one they can't do a thing against is Chara. Chara can overpower their decision to erase the world & stands no chance against them & is unable to dodge infinite damage Chara does to them. Frisk can not undo Chara's erasing & has to strike a deal or forever stay in the void.

Undyne is proven stronger, than Sans, because San's is just learning his patterns, and can only do one damage, Undyne has more health, & is accurate, Sans can only dodge so well because you hit in the same place every time you attack him Undertale, also frisks "Being able to erase the world," Doesn't count, I only admit that Asriel is stronger because he can control time, therefore, stronger.
Undyne The Undying
Literally the hardest and the most unpredictable enemy (second only to sans), still, very hard in general. Also, she is the only monster to overcome determination (Alphys did say monster soul can't contain determination, but I guess Undyne's was too strong, even stronger than death).
She literally wanted to murder you from the beginning, and if you couple that with the fact that she is made out of pure determination on the genocide path and has very quick attacks, I think we can all agree that she is extremely powerful.
Never saw his true power and was most likely holding back while fighting frisk, but he did destroy the mercy button, which is very impressive. He also fought in the war between humans and monsters (probably)
Asgore took me days to finish I coudn't finish him because I didn't even have butterscotch pie or a single healing item, so I quit, you fight him in every route except pacifist.
He can spew fire everywhere, and he can rapidly change the color of his trident to almost always hit you with it. This makes him very powerful.

Same as Papyrus, she's actually pretty powerful and would be a really hard boss battle if you could die, but you can't because she's just so caring...
Okay I think this is fair because she doesn't actually kill you because she backs off on like her third attack.
Toriel is so forgiving and they are really kind and sweet they are the best!

He is stronger than Undyne because of 3 reasons. 1 He can dance on you and make you have to dodge tons of legs. 2. He has mini versions of himself to help protect him. 3. His standard form is indestructible and his EX form has lots of tricks like bombs thrown at you... legs kicked at you... mini mettatons thrown at you... and even his own power source. I think Undyne is strong... but Mettaton is slightly stronger. I think she should go here and Mettaton should go at number 8. Asgore would go to 7.
Mettaton is immortal until you flip their switch, and even when you do, they have that very annoying attack where they throw their soul out (their soul spews out lights which is very hard to dodge).
I think he should be higher one the list because you can only beat him if he has over 7,000 views in the Pacifest route.

He has such precise control of his attacks to weaken you to 1 hp, also in true pacifist when Flowey traps everyone with vines, he uses 2 vines for everyone but Papyrus, Flowey used more than 2 vines.
Papyrus may be stronger than you think, he has such percise control of his magic to make you to 1 hp without killing you, also in the true pacifist route, Flowey uses 2 vines to tie everyone except for Papyrus, Flowey used more vines.
Papyrus does actually have some pretty strong moves, we just never get to see them most likely because ether Papyrus is just a big hearted dork, or it was that dog.

Alpys is just great they always try to impress the player in pacifist route. She is very kind and weird in her own way.
She only attacks you once and its while shes a lost soul. It ends up being a little bit of Mettaton's attacks
We all know why she is here.