Marvel Comics

Background Information
The main competition for DC Comics, Marvel is a comic book publishing company that created many iconic superheroes. Recently Marvel has been milking their creations for all they're worth by making movies for practically every character they have. Some of these movies (e.g. Iron Man) are better than others (e.g. Spider-Man 3) but they have been pretty successful in general.

Something notable about Marvel is they have never needed or pursued a permanent line wide title reboot, which means that since Marvel's modern inception in the 60s, all comic titles that haven't suffered retcons later are canonical to the "main" (sometimes numbered 616 out of all the possible universes) Marvel universe, with the exception of non-canon imprints (like The End titles), separate universe imprints (like What If? titles and Ultimate Marvel/Ultimate Comics titles - not to be confused with Ultimate Collections, which are trade paperbacks for any title collecting more issues than normal-) and series that creators state are not in continuity.

The one constant is the fact that, relative to current events in comics, the formation of the first modern super-heroes happened a bit over a decade ago. NEVER think too much about time in comics beyond that simple premise.

Standing in the Arena
Marvel is considered to be the strongest, universe (well technically Omniverse+) in fiction, since they do have the most powerful being in fiction ever created: Squirrel Girl.

Average abilities in the Marvel universe are super strength, super agility, super spandex, and the fact that you only need pretty much to add water to get artificial intelligence.

Character Profiles
Heroes:

Spider-Man

Iron Man

Incredible Hulk

Thor

Wolverine

Iron Fist

War Machine

The Thing

Captain America

Ghost Rider

Silver Surfer

Nova

Neutral:

Deadpool

Asgardian Destroyer

Galactus

Odin

The Living Tribunal

One Above All

Villains: (Note: Specifies the default alignment, as some ally with the heroes)

Venom

Carnage

Ultron

Magneto

Dormammu

Blackheart

Taskmaster

Amatsu-Mikaboshi

Thanos