I have had the chance to host over 30 of these DC popularity tournaments in the old DC Comics forums where each winner gets to retire from the tournament except for a future tournament where all of the winners meet each other and I had to take a break to get my first 2 graphic novels finished by writing and producing them and now they're also soon going to get published by 2 different publishers.
You vote for the one who you like more, not who's the strongest in a fight and have fun:
Swamp Thing (Alec Holland) vs. John Constantine
Brainiac vs. Apollo
Sandman (Morpheus) vs. Poison Ivy
Starman (Jack Knight) vs. Amazo
Brainiac 5 vs. Ra's Al Ghul
Green Lantern (Kyle Rayner) vs. Donna Troy
Halo vs. Black Adam
Superboy (Kon-El) vs. Lex Luthor
Mr. Terrific (Michael Holt) vs Starfire (Koriand'r)
Firestorm (Raymond & Rusch) vs. Golden Glider
Blue Beetle (Jaime Reyes) vs. Nite Owl (Dan Dreiberg)
Harley Quinn vs. Mera
Black Lightning vs. Lightning Lad
Red Hood (Jason Todd) vs. Metallo (John Corben)
Arsenal (Roy Harper) vs. Cheetah (Barbara Minerva)
The Spectre (Jim Corrigan) vs. Looker
Batwing (Luke Fox) vs. Solomon Grundy
Metamorpho vs. Professor Zoom
Icon vs. The Penguin
Static vs. Mr. Mxyzptlk
Plastic Man vs. Elongated Man
Captain Atom vs Dr. Manhattan
Supergirl (Kara Zor-El) vs. Mon-El
Wonder Girl (Cassandra Sandsmark) vs. Starro
Etrigan the Demon vs. Gentleman Ghost
Cyborg (Victor Stone) vs. Frankenstein
Dawnstar vs. Sinestro
Batwoman (Kate Kane) vs. Vibe
Timber Wolf vs. Shade (Richard Swift)
The Question (Vic Sage) vs. Rorschach
Shining Knight (Ystina) vs. Lobo
Catman vs. Despero
Star Sapphire (Carol Ferris) vs. Black Manta
Orange Lantern (Larfleeze) vs. Vandal Savage
Nightshade vs. Silk Spectre (Laurie Juspeczyk)
Fire vs. Ice
Killer Croc vs. Parallax
Atom (Ryan Choi) vs. Two-Face
Green Lantern (Guy Gardner) vs. Morgaine le Fey
Beast Boy vs. Vixen
Ambush Bug vs. Toyman (Winslow Schott)
Bunker vs. General Zod
Raven vs. Klarion the Witch Boy
Bronze Tiger vs. Lady Shiva
The Creeper vs. Red Lantern (Atrocitus)
Ragman vs. Cheshire
Ocean Master vs. Mirror Master (Sam Scudder)
Geo-Force vs. Heat Wave
Deathstroke vs. Grifter
Spoiler vs. Weather Wizard
Bane vs. Midnighter
The Flash (Barry Allen) vs. Scarecrow
Orion vs. Big Barda
Lady Blackhawk vs. The Brain
Green Lantern (John Stewart) vs. Hawkgirl (Kendra Saunders)
Miss Martian vs. Livewire
Thunderbolt (Peter Cannon) vs. Ozymandias
Robin (Damian Wayne) vs. Mongul I
Gorilla Grodd vs. Monsieur Mallah
Mr. Freeze vs Killer Frost
Katana vs. Jade
Mad Hatter vs. Giganta
Peacemaker (Christopher Smith) vs. Comedian
Batman (Terry McGinnis) vs Bizarro