Dont think there was a single halo match up yet so heres the first

Gyutaro is infected by the flood

For those who don’t know what that is, its a kind of zombie plague made up of the corpses of gods that may or may create and then not wipe out entire galaxies for their space hippie esqu religion 

One of the flood infection forms we are most well versed with are the combat forms so lets say gyutaro inhaled some flood spore and has been turned into a combat form

Considering regular humans can go on to fight Spartan 2’s in the mark 5-6 armor this would require them to get dozens to hundreds of times stronger minimum.

So, can Gyutaro wipe the verse, the verse obviously includes everyone from tanjiros siblings to yoricchi to the forest demon muichiro killed.

On top of that they will be at their theoretical peak, for instance tanjiro is 13th form but doesn’t have a tumor growing out of his head, or white haired muzan isn’t under the effects of drugs 1-4 but characters like rengoku tengen or shinobu don’t just get the mark.  However they will have the MST or Death amps already active.

Characters that normally hold back will fight at 100% strength no matter what.

And demons that cannot die under most circumstances can die here if their brains destroyed. 

 There will 0 infighting

Muzan has zero authority over gyutaro

R1-Gyutaro(feral stage)  
R2-Gyutaro(coordinated via proto gravemind)  
R3-gyutaro(coordinated via a Keymind)  
R4-Gyutaro(directly controlled by the Primordial one) 

Flood Infected gyutaro Vs the verse