Easiest would be if you remove the teeth in illustrator and only keep the core shape.
– Then you create the straight teeth on a copy of the shape using a fat stroke with dashes.
– Add a “trim path” with its “end” around 92%, so 1 of them is missing. Animating the Trim Path offset will now rotate the cogs.
– select the Shape’s Path and run the “Create Nulls From Path” script with the option “Trace Path”
– parent your 1 irregular triangle tooth to this null, now line up the animation of the trace path with the Offset of the trim paths so the null is right in the center of where the 1 dash stroke is missing.