Transformers has a couple of particularly weird variants. First off, there's guys like Transquito, who can spit out a missile. Secondly, there's Nightscream and his teeth-on-a-string trick from Beast Machines. Finally, there's guys like Beast Wars Megatron and Cheetor's Transmetal form, who can fire energy blasts from their alt-mode's mouth in robot mode, which uses said mouth as a hand, but don't seem to have the ability in beast mode for whatever reason.
Unicron fires a green-blue plasma-like ray of energy from his robot head mouth in Transformers: The Movie, and has a powerful tractor beam in his planetoid-mode mouth.
In Transformers Animated, Starscream's head can fire a beam now due to the Allspark fragment in his face.
Is there a continuity the Dinobots have appeared in which they HAVEN'T had a breath weapon? Dinosaurs Are Dragons, after all.
Subverted in that many Transformers with beast modes, even ones based off of mythical beasts like dragons (Snapdragon, Hun-Gurr, Sinnertwin, etc), don't have breath/mouth weapons. Sky Lynx has a laser cannon in his dinobird section's mouth but no weapons at all in his lynx section.