What sort of a plate is the Sunda plate? I have read that the islands of Sumatra &amp; Java have resulted from the subduction of oceanic crust of the Indo-Australian plate beneath the Sunda plate. I want to know whether this boundary is ocean-ocean convergence or ocean-continent convergence.

Are islands of Sumatra and Java like Mariana Islands which result from the subduction of the oceanic Pacific Plate beneath the oceanic Mariana plate? Or are they like the Andean volcanic continental Arc which results from the subduction of the oceanic Nazca plate beneath the South American plate.
Well, in short, it's mainly continental, (oceanic-continental convergence).
But in regards to the &quot;type of plate&quot; that the Sunda plate is, is minor plate or tertiary plate. Meaning it's not very big etc. Because 1 tectonic plate can have both oceanic or continental crust. Tectonic plate and crust are slightly different concepts. So, The Sunda plate is mainly comprised of continental crust. There might be a bit of oceanic crust, but less.
Map of oceanic crust on earth: https://www.ngdc.noaa.gov/mgg/ocean_age/data/2008/ngdc-generated_images/whole_world/2008_age_of_oceans_plates.jpg