No, he CAN learn Martial Arts. Optional things aren't canon. Trevor broke into multiple military bases, more then a few times, he also stole a few military vehicles and aircrafts.
If Trevor gets close to CJ, he's dead, as well. Not to mention, Trevor himself has military training, basic, as well as airforce. As well as a more powerful arsenal of weapons due to the times.
CJ can't be compared in intelligence to Trevor. Trevor has pulled off some amazing heists thanks to his brilliance. He had the plan to steal one of the most rare items of the U.S. and get it back to his base. (He did have to return it, due to the heat he'd get later on, but still.)
To come up with a plan like that, multiple plans, getaway drivers, a big heist like the union depository.
Trevor had a hand in almost all heists, and they all went by almost flawlessly.
As for the Jet, Trevor has a more powerful one and several helicopters.