Is this the biggest mixed bag of a pokemon?

Shell Armor in terms of design and theme, fits Samurott perfectly like a glove. Any other "fitting" ability would make slightly less sense in comparison. However, it learns ZERO defense boosting moves. Which is the only reason you would even worry about getting crited

I'm unsure if Samurott got shafted on the movepool department(no moves that would highlight the importance of a crit immunity) or hidden ability(would benefit from an offensive-based ability more)