Valmiki Ramayana Bala Kanda Sarga 17 Shloka 23

कामरूपबलोपेता: (all these monkeys were endowed )with the powers to assume any form at free will and possessed strength, यथाकामम् freely, विचारिण: wanderers, दर्पेण च in arrogance, बलेन च by prowess, सिंहशार्दूलसदृशा: like unto lions and tigers.

They were endowed with the powers to assume any form at will. They possessed enormous strength and power to freely wander in forests. They were like lions and tigers in pride and prowess.