How will it manage to launch a guts-boosted return? Toxic orb only activates at the end of the turn, by which time Infernape is in and lol'ing at the not-OHKO damage it took.
Infernape outspeeds, and unboosted return doesn't OHKO it, so even if it uses Return on the switch Infernape can CC for the win, since it doesn't have Quick Feet.
Feraligatr @ Mystic Water
Lax/Torrent
252 HP/4 Atk/252 Def
~ Hydro Pump
~ Aqua Tail
~ Swords Dance
~ Return
Infernape can't 2HKO, Torrent Aqua Tail is an easy KO, Hydro Pump is a lolKO.
It beats Machamp regardless, Superpower wouldn't 2HKO even without the statdown, and that means none of the others will 2HKO either, while Feraligatr outspeeds and Hydro Pumps twice.