Shuckle is absolute taunt fodder. It usually carries Stealth Rock, Sticky Web, Toxic, and Infestation or Rest( for the infamous Restochesto combo). It gets shut down by any taunter, and its terrible speed doesn't help, either. Shuckle is very passive and deals very little damage due to its absolutely pitiful damage output(base 10 attack). It is set-up fodder for common set-up sweepers. Also, its huge bulk is nerfed by its horrendous base 20 HP stat. It can be good, but it gets shut down by taunter leads, and set-up sweepers.
This is proved by Shuckle's PU smogon entry in SM
"the rest of its stats are utterly atrocious, with absolutely no offensive presence, the lowest base Speed in the game, and a low HP stat that its defenses do not appreciate. Furthermore, it faces a good amount of competition from other Sticky Web setters, such as Smeargle and Leavanny. On top of their much higher Speed stats, Smeargle has a better support movepool with access to moves such as Spore and Taunt to give it an easier matchup against slower foes and Nuzzle to cripple faster foes. Leavanny provides an offensive presence that threatens entry hazard removers such as Skuntank and has support moves of its own such as Magic Coat, which helps against opposing leads and Taunt users."
Hope this helped!