I lived in Thailand for 8 years and most of the apartments I lived in had gyms. The only time I remember seeing a foreign trainer (or any trainer) was in jomtien. He got asked to leave the apartment gym as he was not a resident. I'm in Vietnam now, been here around 4 years on and off, and I go to big gyms now as the apartments tend not to have gyms included. I have seen one martial arts trainer who was not Vietnamese, so I think it's possible in Vietnam at least, and maybe Thailand.
yes... I needed to do all of this as I'd already pre-booked my bus ticket to Pattaya with not much time to spare from landing to bus leaving so I would have wasted 120b if I didn't run past all the people in front of me on the plane... So glad I pre-booked as well as it was a 3 hour wait for the bus if I had not of done this.