Ratchet

Ratchet never lose his medical skill even he getting rust and also most valuable member of Society's Robot troops

Canon bio
The Autobots' medical officer, Ratchet has a dry wit, often giving his wounded comrades a hard time for taking hits he somehow avoids. With the Energon supplies becoming less and less, he works to find new ways to make do, and he'd really prefer if the Autobots didn't risk injury (or worse) to protect humans.

Ratchet made his name during the Praxian stalemate. He and Bumblebee fought in a few battles together, during which he taught the younger Autobot how to apply first aid. He repaired his throat after Megatron destroyed it in revenge for ejecting the AllSpark into space, enabling Bumblebee to speak from time to time.

After Megatron invaded Iacon and took the Plasma Energy Chamber, Ratchet welded Ironhide's face and stabilized Omega Supreme's condition. When Optimus Prime asked Ratchet if Omega was ready to fight again, the offended medic responded that if Optimus wanted Omega to fight after the Seekers blew him out of the sky, Dark Energon-infused gladiators attacked him and Megatron tore out the Chamber out of his chest, then he wanted another surgeon. Optimus knew he had to apologize but was too preoccupied with rescuing Sentinel Prime.

When the Autobots left Cybertron on the Ark, Ratchet informed Optimus and Ultra Magnus that Omega was repaired and ready to distract Trypticon.

Ratchet was stationed at the Autobot base on Earth, opening the GroundBridge for Optimus to retrieve Arcee and Cliffjumper. He reattached her arm after Starscream had blown it off.