I am a Sri Lankan passport holder and I'm planning to visit Bangkok from Trichy, India with Air Asia or Malindo Air. Do I need a transit visa at Kuala Lumpur International Airport on arrival?
According to Timatic*, the database used airlines, you do need a transit visa for Malaysia, as well as the Thai visa.
Passport holder of Sri Lanka
Transit countries/territories Malaysia
Visa & passport information
Destination - Thailand (TH)
Nationals of Sri Lanka with an emergency passport.
Passports and other documents accepted for entry must be valid for a minimum of 6 months from the arrival date.
When nationals of Sri Lanka travel with an emergency passport, it must be valid for a minimum of 30 days from the arrival date.
Passengers with a transit visa issued by Thailand for a maximum stay of 30 days. They must have a confirmed onward ticket to a third country.
Visitors over 12 years of age with a visa must hold sufficient funds to cover their stay (at least THB 20,000.- per person or THB 40,000.- per family). Proof of funds includes Letters of Credit, vouchers, MCO's or well-known credit cards, which are honored in Thailand.
Visitors who are visa exempt but do not hold return/onward tickets could be refused entry.
Transit - Malaysia (MY)
*Courtesy of Emirates web site sharing of the tool.