Just get someone else with good Special Defense and Defense like Walrien with leftovers and the swallow-stockpile-spit-up build and maybe snow squall or the like and outlast him like a true annoying battle tree fighter.
No-guard makes it 100٪, but Machamp's base speed is lower, so you could still outspeed it, hypothetically speaking. I'm retesent to use an electric or grass type, because that seems too easy.
