Hey @Lmpkio I think there's been a slight misunderstanding. 
Oram didn't change Kuro's gravity, he changed his own. 
To make it easier (hopefully)
-He made himself lighter to be faster
-charged in front of kuro
-moved to the side
-jumped in the air
-made himself very very heavy to drop down and punch the crap out of kuro

Sorry I'll try to be more clear in the future ^^"