Also @ Ginganinja
Whil Scizor doesn't beat all of those pokes, it fares great against most of them, and can pick them off with BP if they have lost a little health beforehand. Not only this, but Scizor will be able to scout any dangerous pokes moves and items with Gliscor's Sub, making it much easier to deal with them.
EDIT: Oh and Genesect doesn't have Pursuit, which is necessary to trap Starmie, Lati@s and Celebi, which would otherwise get in Keldeo's way.
Yea, I don't think your getting my point, Gliscor will not always have a sup up, and my argument is that I would prefer a more stable core, than us chucking on Scizor and saying "look it beats all these pokemon" when it actually doesn't really. From your list...
Latios
Latias
Celebi
Tornadus-T
Gengar
Reuniclus
Starmie
Venusaur
Amoonguss
DD Salamence (if we don't use HP Ice on Keldeo)
Celebi, Latios and Latias are risky vs Scizor, since all commonly carry HP Fire, sure you can BP for a punch of damage, or you can Pursuit if you predict the switch, but its a 50/50 prediction, and if you fuck up you just lost your Scizor. When you consider that Gliscor and Keldeo BOTH lose to these pokemon, I prefer something a little more stable.
Tornadus-T, Reuniclus. Salamence, Amoonguss and Gengar (yep, ill give you these) provided Gengar isn't MYSTIC.
Starmie and Venusaur I don't really consider you beating. Starmie I guess maybe, but you cannot actually switch in on it since your taking a truckload from Surf, if Rain is up then your losing more. Venusaur just tanks your Bullet Punch, kills you with HP Fire, then Giga Drains on Keldeo / Gliscor to heal itself back up.
My point is that Gliscor won't always be able to get that Substitute for Scizor, and if it doesn't half the mons on your list become more threatening. If Scizor doesn't have a Sub, it flat out loses to some of the above pokemon as well, which further refutes your claim that "Scizor deals with every single one of the pokes that threaten our KeldOr combo". Furthermore, we cannot actually switch into many of the above mons on your list with Scizor making it more difficult to play around them. I am well aware that nothing can really counter all of the mons on your list, but I don't think Scizor is the best option despite what you claim.
On Genesect, yea o.k, it lacks Pursuit, but instead you get to force them out, force hazard damage on something, a free hit on something (U-Turn), AND the good matchup on whatever the bring in. Besides, I am not actually nominating Genesect, its too early in the process for us to select our revenge killer, and would rather we get a second substitute receiver before moving on.