Well, in regards to Orthodox communities, while it does not number up to how it is in the other countries, there are Orthodox communities nonetheless. For Singapore, there are Coptic, Russian, Greek Orthodox(EP), and Syriac Malankara. There is also an Old Calendarist community in Singapore.
As for Malaysia, there are only 2, but all concentrated in different cities and states. The more established one is currently the Syrian Malankara Church, whose priest is a friend of mine. I live about 45-50 minutes away from the church, which is located in Kuala Lumpur's version of "Little India".
The other church is located in the historical city of Melaka(2 hours away from KL), and is a Coptic Orthodox Church. Their priest is Fr. Joseph Sim(yes, a Chinese man!)I have no idea where the church is in Melaka (Melaka being my hometown) but for some reason, every Christian presence in Malaysia begins with Melaka. Roman Catholicism started off in Melaka when the Portuguese conquered in 1511(I'm a descendant), Protestantism in 1641 when the Dutch defeated the Portuguese, Anglicanism later when the British took over and now the Copts. No record is known of their origins but there must have devout Egyptians.

There is another Greek Orthodox community in Malaysia and is cared for by the same priest in Singapore. They have a lay leader and they meet for Matins every Sunday morning, and Divine Liturgy when the priest is available for it. Divine Liturgies are held at the Syriac Malankara Church or the chapel at the Russian Embassy in KL when it is scheduled.