any train or bus from guangzhou to shantou?

Yes, there are both trains and buses to reach Shantou.
To reach Shantou, you can take the trains from Canton East Railway Station. For bus, you can take them at Provincial Bus Station near the local railway station. The trains take about 7 hours and the bus take about five hours and a half to six hours.
The buses will reach Shantou directly.
By the way, Shantou and Chaozhou are two different cities.