I didn't mean it in the sense of skipping the second evolution. I meant does the evolution to the third stage still work if do the trade with a first stage instead of a second.
Sorry for the confusion.
I'm not exactly sure as to how that's different than skipping the second evolution. The Pokemon
must be in its second evolution to evolve into its final one. If it's traded while in its first evolution, then it simply trades like any other Pokemon and nothing happens.
If you're talking about the second Pokemon being traded in the evolution trade, then that Pokemon can be anything; if a Machoke and Magikarp are traded, then the Machoke will still evolve to Machamp. But you can
never make a Machop evolve into Machamp through trading. You
must trade it as Machoke for it to evolve to Machamp. Hope this clears up any confusion you may still have.