In the given sentence "Rohan tahalne ja raha hai" (Rohan is going for a walk), what class of verb is used ?

The primary action of walking or moving ('tahalna' / 'ja raha hai') does not require or possess a direct physical object to receive the action. Verbs that pass no action to an object are Intransitive verbs. Since the meaning is fully absolute and complete on its own, it constitutes a Complete Intransitive Verb (Poorna akarmak kriya).