Void's corruption is possibly their only wincon but Mario's wincons are out of character the guy has four resurrection so his fax hax don't make void instantly incapacitated. Mario's wincons are time travel, EE, possession, summoning, sealing, mind control, reality warping this is all the hax that are capable of working on Void and are offensive let's explain why none of these are happening.
Time travel we don't know how it works, EE is to slow, cappy probably gets vaporized before this is possible, summoning there is a statement that implies the Zeekeeper can choose not to be summoned and summoning him would be out of character since Luigi is not here, sealing was never used against boss or serious battle, Mario used the music keys only to undo their effects reality warping or mind control.
Why is it more likely void corrupts him? Because there is no evidence it has helped him win battles that don't directly effect princess peach's kidnapping status for example in paper Mario he died trying to stop bowser from kidnapping her. Mario has been captured in paintings several times and sent thousands of miles away from rescuing her.
But if Mario is corrupted how will he save peach it seems being beaten unconscious make the corruption end so he just gets beaten unconscious after he loses.
Void wins