In this work, we provide an overview of the state-of-the-art flexible two dimensional radio frequency transistors based on graphene, MoS2 and black phosphorus for nanoelectronics applications from baseband to sub THz, with outstanding electrical performance obtained fulfilling the requirements of both high speed operation and low power consumptions. Flexible RF transistors based on graphene with intrinsic cutoff frequency (fT) reaching 100GHz enable sub-THz flexible nano systems. Large scale CVD grown MoS2 based flexible RF transistor was realized for the first time with record intrinsic fT ~ 5.6GHz which can afford low power RF nano systems. In addition, black phosphorus based flexible transistors and circuits have been realized with outstanding electrical performance in both DC and high frequency applications while retaining mechanical robustness.