Lets see...
Magnezone has weakness. That alone makes things rough on the Zone. Even then Champ struggles with Cyber Shock followed by Gyro Ball KO's, and Zone X doesn't have that nasty weakness.
Scizor has bigger worries then Machamp.
Jumpluff's resistance means that Machamp cannot 2HKO him unless he uses Champ Buster. That move is an indication that somewhere on Machamps bench (And probably the Champ himself), something is going down to Pluff next turn.
Kingdra is for all intents and purposes faster then Machamp, prime included. Kingdra consistently 2-shots Machamps for 1 energy, Machamp cannot say the same for 3 energy. Don't come with the "Champ can donk Dra" argument cuz in this case, that happens to work both ways.
Mind you, I'm talking about Straight Champ SF with Champ Prime tech here, not decks like DonChamp. Just the old fashioned donk deck that use Champ Prime for their "big damage".