I'm going to have to think this through before I make my decision...
Machamp is a powerhouse, but could easily be taken out by Alakazam.
Alakazam has the brains to win, but could overlook the lesser threats like Jumpluff and Bidoof.
Zoroark's illusion ability could be an advantage, but could still be taken out by Machamp.
Blissey has good defenses, but again Machamp still wins in a matchup.
Wobbuffet has Counter and Mirror Coat, but I'm sure Alakazam could figure out a way to avoid that.
Bidoof could be overlooked by the other contestants, but would fail miserably in a one-on-one.
Jumpluff, see Bidoof.
Mienshao, see Machamp to a lesser extent.
It would probably end up as a face-off between Alakazam and Wobbuffet. The end result would all depend on if Alakazam could avoid Counter and Mirror Coat.