I thought up this cool fandom fighter idea, with characters big and small in pairs of themes, here are the characters:
Ninjas: Bio Spark-Sheik
Memelords: SMG4-Armstrong
Limbless: Susie-Rayman
Greedy: Shovel Knight-Wario
Wrestlers: John Cena-Incineroar
Dragons/Rulers: Ridley-Hiccup/Toothless
Offspring: Tetra-Gohan
Punchers: Knuckles-Popinski
Darkened: Riku-Antasma
Assasins: Wolf-Bete
Summoners: Bea-Jotaro
2D: Mr. G&W-Bill
Honor: Ryu-Marth
Tacticians: Master Cheif-Ludwig
Demons: Kazuya-Piccolo
Aware: Deadpool-Dora
Cats: Taokaka-Beerus
Justice: Undyne-Obi Wan
Hats: Terry-Hat Kid
Forgotten: Raditz-Snoke
Killers: Michael Myers-Black Baron
Dogs: Hot Dog-Bolt
Broken: Invincible-Iron Giant
Alts: Red Son-Blueberry
Kamikazes: Saibaman-Bob Omb
Transformed: Meggy-Frost
Masks: Joker-Dimentio
Blues: Boyfriend-Megamind
"Doctors": Zomboss-Eggman
Archers: Claude-Circus Baby
Marios: Paper Mario-Speedrunner Mario
Gods: Frisk-Zeno
Here are links to Tier Lists and Brackets: Create a Media's Greatest Battle (Random Stuff For Random Things) Tier List - TierMaker and https://bracketfights.com/create/medias-greatest-battle-just-kinda-random-46327
Also, if you want to know what I feel the tier list for the game would be (For context, the "Power Level", or power of mechanics, of the game would be around GG Strive to SFV level), well...
...It's your problem now (This isn't discussing who is strongest with power levels, this is who is most viable in this supposed fighting game, at least at first), have fun in the replies!