So I looked at https://pokemonrevolution.net/forum/viewtopic.php?t=34240 and didn't find Shell Smash as not coded or bugged.
According to your Pokédex, Clamperl doesn't learn Shell Smash at level 50; in fact, it doesn't learn it at all in this game. I've had a similar case in which Nuzleaf was going to learn Leaf Blade at 27~29, but didn't because Pokédex said it doesn't learn it.
Anyways, if this is already mentioned somewhere, I apologize.
Pokemon: Clamperl
Move: Shell Smash
Etc: Clamperl is suppposed to learn Shell Smash at level 50, but it doesn't seem to be coded or mentioned in the linked thread. I really need this.