I played Pokemon Go during my holiday in Kuala Lumpur a few months ago and discovered the following:
I read that using incense we are able to attract more exotic Pokemon so we decided to do that while driving down the highway. However, traveling at 110 kilometers an hour made it impossible to catch any Pokemon the incense attracted. The incense was not very effective, it only attracted five to ten Pokemon. The ones we encountered were difficult to catch and the ones we caught would always escape.
Malls in Kuala Lumpur are better
I was unable to use GPS on my Note 3 in any of the malls in Penang but had no problems in any of the malls in Kuala Lumpur. I guess it is the way the antennas are set in the malls in Kuala Lumpur.
Mid Valley was the best mall we visited to catch Pokemon. Seems that there was different spawn schedules, some days we found many Pincers and other days we found Scyther. We also found Pikachu spawns at Sunway Pyramid.
Taking over gyms in the Mall was challenging. As soon as we defeated the gym, somebody would place the Pokemon in it (before we have a chance to place our own).
Isolated Pokestops are not good hunting ground
We went to a few Pokestops located in skate parks in Kuala Lumpur and Putrajaya. The spawn rates at those stops were very low, even with lure modules. Only common Pokemon like Pidgey and Ratata spawned.
Looks like the frequency of spawns and variety is dependent on the number of players near the Pokestop.