First film Optimus has 3 Bumblebee has 2 Ironhide has 2 Jazz has 2 Ratchet has 1 Megatron has 2 Starscream has 4 Bonecrusher has 1 Brawl has 1 Barricade has 2 (going into car mode counts, right?) Frenzy has 2 (going into phone mode counts as one) Blackout has 2 So about 24
Barricade had 3 in the 1st movie. (when Sam thinks he's a cop; back to car mode; to fight Bumblebee) EDIT: Bumblebee had at least 3 too EDIT: and Optimus had at least 4
These are my calculations: Transformers - 45 Qatar Base Attack Blackout Vehicle-to-Robot Frenzy and Air Force One Frenzy Vehicle-to-Robot Barricade’s Interrogation Barricade Vehicle-to-Robot Bumblebee vs. Barricade Barricade Robot-to-Vehicle Bumblebee Vehicle-to-Robot Barricade Vehicle-to-Robot Bumblebee Robot-to-Vehicle Autobots’ Arrival Optimus Prime Meteor-to-Protoform Optimus Prime Protoform-to-Vehicle *See last bit Optimus Prime Vehicle-to-Robot Bumblebee Vehicle-to-Robot Ironhide Vehicle-to-Robot Jazz Vehicle-to-Robot Ratchet Vehicle-to-Robot S7, Bumblebee’s Capture Bumblebee Robot-to-Vehicle Jazz Robot-to-Vehicle Ratchet Robot-to-Vehicle *Didn’t count Ironhide, he’s practically invisible in the shot Jazz Vehicle-to-Robot *Obvious, but visibility blocked by column Bumblebee Vehicle-to-Robot S7, Hoover Dam AllSpark Mass-shifting Bumblebee Robot-to-Vehicle *See only last few frames of transformation Starscream Vehicle-to-Robot Megatron Robot-to-Vehicle Starscream Robot-to-Vehicle Megatron Vehicle-to-Robot Starscream Vehicle-to-Robot Highway Battle Bonecrusher Vehicle-to-Robot Optimus Prime Vehicle-to-Robot Mission City Battle Ironhide Vehicle-to-Robot Ironhide Vehicle-to-Robot Jazz Vehicle-to-Robot Brawl Vehicle-to-Robot Megatron Vehicle-to-Robot Blackout Vehicle-to-Robot Blackout Robot-to-Vehicle Starscream Vehicle-to-Robot Starscream Robot-to-Vehicle Optimus Prime Vehicle-to-Robot Megatron Robot-to-Vehicle Megatron Vehicle-to-Robot Starscream Vehicle-to-Robot Blackout Vehicle-to-Robot Starscream Vehicle-to-Robot Starscream Robot-to-Vehicle Starscream Vehicle-to-Robot Transformers: Revenge of the Fallen - 43 Shanghai Shootout Ironhide Vehicle-to-Robot Demolishor Vehicle-to-Robot Arcee Vehicle-to-Robot Sideways Vehicle-to-Robot Sideways Robot-to-Vehicle The Twins Vehicle-to-Robot Sideswipe Vehicle-to-Robot Optimus Prime Vehicle-to-Robot Optimus Prime Robot-to-Vehicle Optimus Prime Vehicle-to-Robot Bumblebee’s Backward Barbeque Dick-Bot, The Blender Appliance-to-Robot Ejector Appliance-to-Robot Dyson Vacuum Cleaner Appliance-to-Robot Microwave-‘Bot Appliance-to-Robot CISCO Aironet Appliance-to-Robot Bumblebee Vehicle-to-Robot Diego Garcia The Twins Vehicle-to-Robot *Obscured by curtain The Twins Robot-to-Vehicle *Obscured by curtain Optimus Prime Vehicle-to-Robot Reedman’s Theft Micro-Cons Ball Bearings-to-Robot Reedman Robot-to-Reedman Nemesis Ship Sequence Megatron Vehicle-to-Robot Chop-Shop Sequence Wheelie Vehicle-to-Robot Alice at College Alice Human-to-Pretender Alice Human-to-Pretender *Cut short Sam’s Interrogation Scalpel, The Doctor Microscope-to-Robot Megatron Robot-to-Vehicle Forest Battle Optimus Prime Vehicle-to-Robot Megatron Vehicle-to-Robot Grindor Vehicle-to-Robot Starscream Vehicle-to-Robot Post-Forest Battle Megatron Vehicle-to-Robot Starscream Vehicle-to-Robot Bumblebee Robot-to-Vehicle Jetfire’s Exposition Wheelie Vehicle-to-Robot Jetfire Vehicle-to-Robot Final Battle Part 1 Megatron Vehicle-to-Robot Devastator Vehicles-to-Gestalt Starscream Vehicle-to-Robot Rampage Vehicle-to-Robot *Cut short Final Battle Part 2 Jetfire Vehicle-to-Robot Megatron Robot-to-Vehicle Optimus Prime Combination Transformers: Dark of the Moon - 55 Chernobyl and Iran Mirage Vehicle-to-Robot Bumblebee Vehicle-to-Stealth Force Optimus Prime Vehicle-to-Robot *including trailer NEST HQ 1-You Lied to Us Optimus Prime Vehicle-to-Robot Africa Megatron Vehicle-to-Robot Starscream Vehicle-to-Robot Assassinations/Acuretta Systems Laserbeak Robot-to-pink Bumblebee Laserbeak Pink Bumblebee-to-Robot Laserbeak Computer Monitor-to-Robot Laserbeak Copier-to-Robot NEST HQ 2-Reactivate Sentinel Bumblebee Vehicle-to-Robot Alien Con-Fab Brains Laptop-to-Robot Highway Chase Crowbar Vehicle-to-Robot Hatchet Vehicle-to-Robot Crankcase Vehicle-to-Robot Bumblebee Vehicle-to-Stealth Force Mirage Vehicle-to-Robot Sideswipe Stealth Force-to-Vehicle Bumblebee Vehicle-to-Robot Bumblebee Robot-to-Vehicle Mexican Standoff/Sentinel’s Betrayal Sideswipe Vehicle-to-Robot Ironhide Vehicle-to-Robot Crowbar Vehicle-to-Robot Crankcase Vehicle-to-Robot Ironhide Vehicle-to-Robot Sentinel Prime Vehicle-to-Robot Sentinel Prime Robot-to-Vehicle Optimus Prime Vehicle-to-Robot Commence Transport Protoform Protoform-to-Vehicle *police car Protoform Protoform-to-Vehicle *garbage truck Dylan’s True Side Soundwave Vehicle-to-Robot Soundwave Robot-to-Vehicle Watch-‘Bot Watch-to-Robot Watch-‘Bot Robot-to-Watch Exile/Destruction of the Xanthium Starscream Robot-to-Vehicle Watch-‘Bot Watch-to-Robot The Autobots’ Return/"Seal off the city" Protoform Vehicle-to-Robot *pickup truck that blasts humans to oblivion Bumblebee Vehicle-to-Robot Mirage Vehicle-to-Robot Que Vehicle-to-Robot *in the background Ratchet Vehicle-to-Robot *in the background The Wreckers Vehicle-to-Robot *hidden by smoke Starscream Vehicle-to-Robot *in the background V-22 Parachute Sequence Starscream Vehicle-to-Robot Sam Rescues Carly Starscream Vehicle-to-Robot *in the background Laserbeak Flat Screen TV-to-Robot Starscream’s Death Starscream Vehicle-to-Robot Bumblebee Vehicle-to-Robot Bumblebee Robot-to-Vehicle Final Battle Dino Vehicle-to-Robot Sideswipe Vehicle-to-Robot Ratchet Vehicle-to-Robot Bumblebee Robot-to-Vehicle *battle with Sentinel Sentinel Prime Robot-to-Vehicle Sentinel Prime Vehicle-to-Robot Bumblebee Vehicle-to-Robot And please, if I've made any mistakes or omissions, let me know.
You also missed during the battle with Sentinel Bumblebee transforms back to robot mode in the same shot where he evades Sentinel.
What about that Decepticon Protoform that transforms from pick-up to robot during the scene where lots of Protoforms arrive to Earth? I call him Dropkick.
Oh yeah! The reason I didn't include him is because I had no idea that he actually transformed. That's one thing that I never noticed. I shall add that. Thanks.