I manage to drop 5kg in less than a month to be upgraded to PES B recently. Even though muscle/fat ratio was roughly the same and had a fairly large bone mass.

Things He's gotta do EVERYDAY
1) Watch your diet, stop eating fatty foods [e.g. Stop eatin fastfood and highly fatted hawker food]. Take off skins of chickens, eat more veg, and especially more protiens [i find 2 half boiled eggs every morning works the best] to build up those pull up muscles. This will help you maintain ur weight in the future as well
2) Run EVERYDAY, Don't care if you jog on days you feel lazy but atleast get out of the house. Run for 20mins minimum. Best times to run is either 8am in the morning or 6:30/7pm at nights. Not too hot at those times. If it rains, go to the gym.

While at the GYM
Running - To loose weight, run in short burst. E.g. Warm up 2mins on Tread speed of 10. Then push it up to say 14 for 2 mins, then lower it back down to 10 for 2mins etc etc. On the odd day, do a full 2-3km at 11/12. If its too quick, start at a lower speed, vice versa if its too slow.
Weights - Pull up muscles simply use the muscles located at the sides where ppl tend to tickle you. Lat Pulldowns & Assisted Pull ups work on these muscles. But i still encourage you to ask the instructors, they know better.
Correct me if im wrong anywhere but this is wat i did everyday for about 3-4 weeks and i managed to drop the weight. Good luck 2 ur friend