If anything, Genesect can take Scizor's place in Gen 5 ubers because Scizor is freaking terrible now with its low speed and almost useless Bullet Punch in a tier full of fire (Ho-oh, Reshiram, Blaziken), water (Kyogre, Palkia), electric (Zekrom, Thundurus) and steel (Dialga, Jirachi, Ferrothorn, Forretress, Arceus-Steel, Genesect) types.
The only thing Scizor was notable for was being able to revenge kill the Kyurem formes with Bullet Punch, but scarf Genesect accomplishes the same with Iron Head and since it has 99 base speed it doesn't need priority to do it.
It's Scizor who has no business in the uber tier now. Its terrible speed doesn't cut it.
Speaking of Genesect, rain teams have started to carry Magnezone to check it. It can come in against any move besides Flamethrower (and rain discourages Genesect from using it) and if it's locked into Ice Beam, Thunder or Iron Head it's dead Gene.