Rafal's not wrong.
Serpent is like a sharpshooter underwater with more range, which is huge.
Terra'd urchins are literally invincible to them. Which makes them feel more like a pain gate than a static defense. They will hit you for so long as you're within their 600 range, and scallops are slooooow. Urchins in general make a lot of cost too.
Claymore kills them one hit in an area of effect for around the same price. Is also faster. Lol.
Hunter beats them for cost with auto-kite, but is a less generalist unit.
Snakes don't beat them straight up, but are very fast and difficult to keep track of. They one shot ducks which makes the raider game a pain in the ass, then will often out maneuver scallops either picking them off or damaging eco/suppressing expansion.
If water is not too deep, wyvern can decimate them repeatedly.
Current iteration of scallop is a good unit, but nowhere near its old power level when it was a skirmisher while underwater. I see them as a vital part of water comp in team games, but in 1v1 especially, amph struggles in the variety of threats they can field. Once scallop is countered further adaptation usually requires fac switch.
