I don't know how tall Pinata gets, but here is a tree with Indica Major rose, growing in the Sacramento Historical Cemetery
Carla in Sac

Most oaks will provide more shade than roses prefer. Possible, yes, but not a preferred support system :-)

This has has been heavily debranched and I planted some full sun perennial under it and they are doing fine. Do i still need to attach some other kind of support to the tree?

You might, depending on far up the branching starts. Roses are not really climbers in the sense that vines are - there is nothing that will help them attach or grow up into a tree or large shrubs other than the thorns on the long arching canes. No vining stems or leaf petioles and no holdfasts or adventitous rootlets :-) They will need some help until they can hit some anchorage for their thorny canes.