There is no way to evolve Machoke without trading at all, but there is a bug in Gen 4 that allows you to evolve Machoke by trading a different Pokemon on the GTS. This is helpful because the GTS never requires to you make a direct connection to another player, which is the problem for a lot of people.
To use the bug, deposit Machoke on the GTS for trade, and request something impossible + valuable in return (ex: level 9 Darkrai) to prevent it from being traded. Then, seek a Pokemon on the GTS and successfully trade for it. Then, return to the deposited Machoke and withdraw it. This process will cause Machoke to evolve, even though it was never traded.
This process requires use of Wiimmfi, a replacement service for Nintendo WFC which went offline in 2014. Instructions for connecting to Wiimmfi are available in this answer. The biggest hurdle to using Wiimmfi is creating a WEP/unsecured access point for the DS, but some smartphones will let you make a hotspot like this.
Obviously, Wiimmfi isn't as active as the real service was in 2007. But since you will be seeking the Pokemon, this won't be an issue as long as something is on there.
