Name : J'onn J'onzz ( better known as Martian Manhunter)
Affiliation : Founding Member of the Justice League of America
Background : Born and bred on the planet Mars, he escaped to Earth when his civilization was destroyed. He shape shifted to look like a human and lived under the name of John Jones. He became an intergalactic law enforcer trapping and enforcing criminals from over 28 galaxies. When earth was in danger, he along with the other superheroes like Superman, Wonder Woman etc. came together to form the Justice League of America.
Name : Vision or Victor Shade
Affiliation : Ultron's minion and Avengers
Background : Vision was created by Ultron, one of the most powerful robotic foes of the Avengers, who had the unique AI to make it able to think for itself. This synthetic humanoid was made from parts of the original Human Torch and the brain patterns of Wonder Man. The Vision was initially tasked to destroy the Avengers before being convinced by them to turn and destroy Ultron instead.
LET THE FIGHT BEGIN!!!!
Trained as a Manhunter in Mars, J'onn J'onzz was basically a part of the Police Task Force in Mars making him an expert fighter and combatant. J'onn is said to be lift more than 100 tons and has locked horns with the likes of Superman and Wonder Woman. He has once even helped them move the Earth owing to his superior strength.
Vision's primary training in unarmed combat came from Captain America. Vision can only lift up to a maximum of 75 tons, any more weight would cause Vision's internal systems to be destroyed due to extreme pressure.
There is very little to choose from here, the final verdict will only rely on how much weight they can actually bear as both seem to be pretty ordinary fighters. So, the winner of this round is Martian Manhunter.
Martian Manhunter - 60/100
Vision - 55/100
Vision's brain is essentially not organic but synthetic. Like Ultron's brain his programming also evolves through experience, thus as time passes by Vision becomes wiser. Vision can also hack into and access all the the computer chips in the world, thus giving him the ability to tap into infinite resources.
On one hand we got a synthetic humanoid who can tap into vast amounts of energy while Martian Manhunter has an IQ of over 192. I call it a draw !!
Martian Manhunter - 90/100
Vision - 90/100
J'onn's main armour are the complex chain bio-molecules in his body. They can be altered at will and can take the shape of anything. The polymer is durable , flexible and incredibly strong. His skin thus absorbs and deflects high velocity projections like bullets, shrapnel and debris. He is also able to phase out thus allowing him to be permeable to any rockets, energy emissions and blasts.
Vision's superior defense seals this round though only marginally.
Martian Manhunter - 85/100
Vision - 90/100
Special Abilities :
While both superheroes can fly, Martian Manhunter flies at supersonic speed whereas Vision can only get up to a maximum of Mach1. While Mach1 may be incredibly fast when compared to the normal human speed, it is in no comparison with that of supersonic levels.
Martian Manhunters main power is the use of telepathy. Unfortunately for him Vision is a synthetic humanoid with all bodily organs made of a special kind of material. However, as shown in the crossover Martian Manhunter can actually tap into Vision's mind as he is 'almost human'.
Vision's Solar Jewel gives him the power to shoot laser and heat vision from what can be called the third eye. Martian has been seen to project X-Rays and heat vision too. However the salient point stands that Martians have a weakness for fire. The weakness has been varying throughout the entire Justice League series with the recent ones showing that he has almost overcome this weakness to fire.
In addition to this the Martian has 9 senses and super-hearing ability which helps him in his tracking and detective activities.
Overall the powers seem balanced but the fact that Vision can do nothing when he is intangible proves a major loss to him. Martian on the other hand has total control of his powers even when he is intangible. Thus this round goes to the Martian, by a small but decisive margin.
Martian Manhunter - 80/100
Vision - 70/100
Martian Manhunter - 315/400