Iron Man defeated
In both Marvel Comics and the MCU, Iron Man is no pushover, but one story showed that even with his full arsenal, he can be taken down singlehandedly by the Guardians of the Galaxy's Gamora.
The greatest and most challenging foe Loki has faced is perhaps his own brother, Thor. While the two were raised as siblings by Odin, envy drove Loki's desire to overthrow Thor., Loki is frequently defeated by the god of thunder, but is never discouraged from persevering in his efforts.
Spider-Man has fought some of the most dangerous foes out there, but his battle with Loki was one of his most unconventional. He tried to fight Loki like he normally would but this was pretty hopeless, as Loki is Spider-Man's superior in every way.
Captain Marvel is the most powerful and powerful Avenger in the Marvel Cinematic Universe (MCU). Her incredible powers and determination have made her a valuable member of the Avengers.
So, when Thanos was about to use the powers of Infinity Stone to kill Iron Man, despite stabbing him already, it was because he did not wish to leave any chance of him surviving. Ironically, it was Tony Stark who defeated Thanos five years later in Avengers: The Endgame.
Really, this wouldn't be much of a fight. There's exactly nothing the Joker could do to hurt Loki. Joker is a ruthless and cunning man, but he's still just a man.
Loki. Loki (Tom Hiddleston) and Doctor Strange have very different forms of magic, which makes comparing them somewhat difficult, but in the end, Loki takes the crown with his mischievous skills and 1500 years of experience.
Besides Kryptonite, magic is Superman's biggest weakness, and as an Asgardian, Loki is a being of magic. He may not be as strong or as fast as the Man Of Steel, but he doesn't really need to be. He just needs to get a few good spells off.
Thanos destroys everyone and everything on the ship. He takes the Tesseract (which has an Infinity Stone inside) from Loki and then chokes the god of mischief until he dies.
Loki regards the Hulk as a danger to society, and, because the God of Mischief is attempting a heel-face turn in order to become a hero, he decides to defeat the Hulk. Of course, even despite his Asgardian strength, Loki is no match for the Hulk so he doesn't bother using his strength to subdue the beast.
Loki's greatest weakness is water and his spells do not work in water.
Mandarin - The archenemy of Iron Man, the Mandarin is a Chinese nobleman, scientist and former diplomat turned criminal mastermind.
Thor beat Iron Man easily. Iron Man was basically powerless against the God of Thunder. Thor stopped short of beating Iron Man to death, but he made sure that Iron Man knew that there was nothing he could do to Thor if Thor pressed the issue.
The Joker is quick-witted and always seems to be one step ahead of his foes, but when it comes down to a battle against Iron Man, he would surely lose. In light of both of their intelligence levels, Joker wins in intuition and trickery.
Loki and Thor are both gods and have immense godly powers that make them somewhat impervious to harm, though they can be beaten; they can lose eyes (Thor) and they can die (Loki). If the metric is physical strength, then Thor is easily the winner.
In the MCU film Avengers: Infinity War, Thanos kills Loki by strangling him to death with the same hand that held the Infinity Gauntlet.
However, he's always been one of the greatest villains in the Marvel Universe, a powerful foe for every hero who has faced him. He's even been able to beat his brother Thor and his fellow Asgardians, conquering Asgard on more than one occasion.
Loki could trick Aquaman, but it's only a waiting game since he doesn't have anything to keep the latter down. Aquaman will be getting back up each time and he has far too much strength on his side for Loki to keep defending against. If an aquatic backdrop is added, then Aquaman wins within seconds.
He attempts to kill Thanos. While he fails, he still took the chance to try and stop Thanos before he could hurt more people. Loki may have been classified as a villain, but he died attempting to be a hero.
Loki would win in a fight against Captain America. This is because the God of Mischief is stronger, faster, more durable, and more intelligent than Captain America. It would, however, be a close call in Loki's favor because Cap's willpower wouldn't allow him to give in even when Loki has the upper hand.
In the aftermath of his failure, Thor had a new-found determination to kill Thanos and undo the Snap. The remaining Avengers converged on the Titan's home to find him wounded and the Infinity Stones destroyed. Seeking vengeance, Thor raised Stormbreaker and, with one fell swoop, beheaded Thanos.
Thor is great at close-range combat, too, which is one of Wanda's weak points. Captain Marvel and Captain Carter were able to get in a few blows before succumbing to the Scarlet Witch, and that is because they got close enough to her to do it.