You vote for the one who you like more, not who's the strongest in a fight and have fun:
Sif vs. Thor (Jane Foster)
Spectrum (Monica Rambeau) vs. The Captain
Toad vs. Nico Minoru
Sabretooth vs. Hairbag
Captain America (Sam Wilson) vs. Nighthawk (Kyle Richmond)
Blue Marvel vs. M
Northstar vs. Howard the Duck
Gamora vs. Justice
Swordsman vs. Blink
Captain Britain (Brian Braddock) vs. Pete Wisdom
Green Goblin (Norman Osborn) vs. Hobgoblin (Roderick Kingsley)
Boom-Boom vs. Captain Universe (Tamara Devoux)
Daimon Hellstrom vs. Magma
Spider-Woman (Jessica Drew) vs. Dormammu
Ronan the Accuser vs. Chase Stein
Beta Ray Bill vs. Surtur
Iceman vs. Electro (Max Dillon)
Frankenstein's Monster vs. Hulkling
Groot vs. Ramrod
Apocalypse vs. Skaar
Ultron vs. Victor Mancha
The Punisher (Frank Castle) vs. Silvermane
Songbird vs. Baron Zemo (Helmut)
Sasquatch (Walter Langkowski) vs. Devil Dinosaur
Gambit vs. Marrow
Hawkeye (Kate Bishop) vs. Ms. America (America Chavez)
Sage vs. Jessica Jones Cage
Thanos vs. Supergiant
Mr. Sinister vs. Ruckus
Morbius vs. Klara Prast
War Machine (James Rhodes) vs. The Living Laser
Sunfire vs. Mikhail Rasputin
Carnage vs. Karolina Dean
Blade vs. Jennifer Kale
Valkyrie (Brunnhilde) vs. Hellcat
Amora the Enchantress vs. Cloak
Nova (Richard Rider) vs. Rage
Cannonball vs. Feral
Kingpin vs. Dagger
Loki vs. Fandral the Dashing)
Misty Knight vs. The Shroud
The Blob vs. Molly Hayes
Warpath (James Proudstar) vs. Caliban
Sauron vs. Old Lace
Colleen Wing vs. Ghost Rider (Johnny Blaze)
Toxin (Eddie Brock) vs. Silk
The Man-Thing vs. Gorgeus George
N'Kantu the Living Mummy vs. Wiccan
Firestar vs. Shocker (Herman Schultz)
Dr. Minerva vs. Mar-Vell
Mystique vs. Pixie (Megan Gwynn)
Darkhawk vs. Squirrel Girl
Sharon Ventura vs. Red She-Hulk
Jubilee vs. Slab
Wonder Man vs. Hogun the Grim
Longshot vs. Namorita
Sandman vs. Volstagg
Speedball vs. Karma
Elsa Bloodstone vs. Black Panther (Shuri)
The Chameleon vs. Patriot (Eli Bradley)
Domino (Neena Thurman) vs. Siryn
Rhino vs. Speed
A-Bomb (Rick Jones) vs. Hazmat
Wolverine vs. Daken