That depends on how you want to use the Shuckle.
Are you actually considering using it as a pokemon to use throughout the game's story mode? Because if you are then Shuckle really is not worth it. Not even a little bit. The only reason to catch a Shuckle in a play through is if you want to fill your pokedex.
If you know people who want to battle using gen 2 games, Shuckle does have a niche there. It has nothing in the attacking or speed departments, but a truck load of defence and special defence. So basically you use Toxic to badly poison your opponent, then have Protect to prevent damage, Rest to restore health if you do take too much damage and whatever you want in the last slot - Sandstorm, Wrap, Withdraw...
Basically, Shuckle is for stalling, sitting there while Toxic takes down your opponent - usable in competitive play but tedious in the actual game itself.