Is it suitable to bring a 4months old baby to genting, malaysia? My in law wanted to bring us for holiday but im not sure if just a 4months old baby able to cope the long journey and the environment there.

If you feel that you want to go then I don't see any issue. I don't understand the multiple comments about stating that it's "cold" or rainy there! People do realise that there are some parts of the world where it's actually freezing and below, right? Babies are allowed to be born in those places ;)