I've noticed this in ROTF. Some characters have their ROTF abilities that they use in the movies. Optimus's increases his melee damage and in the movies he uses melee a lot knocking off peoples heads in the process. Sideswipe manually launches his blades at sideways and slows him down. In the movies Ratchet I see always takes these big hits on the battle field and yet stands back up. In the 1st and 2nd movie Megatron uses his fusion cannon twice and its lethal to anyone but Prime. Starscream could, I mean he's sort of a hit and run charater and it would explain why his weapons are so good. These are just guess's. These go for the movies, I know what they do in the game.
I'll list them all for you because I love lists. Optimus Prime: Temporarily makes it impossible to lose health below one sliver Ironhide: Rocket turret spawner Megatron: One-shot kill Ratchet: Repairs him and allies within the aura regardless of what they're doing Sideswipe: High-damage bomb launcher Jazz: Temporarily doubles speed Seeker: Teleport farther in the direction you are moving Long Haul: Same as Ratchet Grindor: Spawns gatling turret Starscream: Doubles weapon damage and slows down enemies hit by weapons Bumblebee: Temporarily stuns enemies within range Breakaway: Overheats weapons of nearby enemies Aerialbot: Cools down nearby allies and self's weapons Protectobot: Blinds enemies Soundwave: Spawns gatling hovering drone that jams enemy radars (jet mode), spawns stationary Rumble drone (robot mode) Jetpower Optimus: Same as normal but affects nearby allies Jetfire: Reveals enemy locations on the radar Sideways: Spawns mine that slows down enemies near it G1 Megatron: Same as Megatron G1 Starscream: Same as Megatron G1 Optimus: Same as normal Optimus Sunstorm: Same as Breakaway I think that's all of them.
g1 SS is the same as Megatron's only g1 Megatron flies into SS's hand and g1 Sunstorm is the same as Breakaway's
Jetfire's will show an enemys location across the map on his radar making him my favorite to play as. His weapons are so fun to use.