Condition
The effect of Contact “C”'s effect where the controller cannot Fusion, Synchro, Xyz, and/or Link summon without using that card specifically as the material doesn’t seem to exist.
What happened?
It happened on the first turn where my opponent normal summoned Synchron Carrier then normal summoned Junk Synchron in addition to Synchron Carrier’s effect, I activated Contact “C” as it was special summoned onto their side of the field, but my opponent was still able to go out into something like Accel Synchron after.