Other Good matches could be:
Kuuga Rising Ultimate vs Hulk
Agito vs Capitain Britain
Knight(Wing Knight) Survive vs Batman
Faiz vs War Machine
Blade vs Shatterstar
Hibiki vs Iron Fist
Hyper Kabuto vs The Flash
Den-O vs Kang the Conqueror
Dark Kiva vs Ghost Rider
Decade vs Galactus (I know it's unfair but this is the destroyer of words vs the devourer of worlds!)
Double vs Storm
OOO vs Darwin
Fourze vs Green Lantern
Wizard vs Doctor Strange
Zangetsu vs Capitan America

That is a more suitable match for OOO than Spiderman. OOO's multiple combos vs Darwin's adaptability sounds more like a better battle. With Spiderman, there's the argument about his intellect and his webbing vs Eiji's spontaneous behavior, but uniform start in battle. At least with OOO and Darwin, it's a battle of adapting to what they pull next.

What do you think...

if Spider-Man was controlled by the symbiote

and Eiji/OOO was controlled by the purple medals?

Do the symbiote and purple medals seem similar?

The Purple Medals enhance Eiji's powers but make him much dumber.

The Venom Symbiote enhance Spider-Man's powers but make him more aggressive.

I still think the match goes to Spidey, since his intelligence is still intact.

Not dumber. Hell no not dumber. FERAL is the word you're looking for.