I really wouldn't go with Life Orb or Expert Belt on the Shell Smash set. I run Liechi Berry on mine. The cool thing about Sturdy on Crustle is that it essentially acts as Focus Sash without taking up an item spot. The idea is to send him in when there are no entry hazards (a Rapid Spinner would be a good addition to your team.) I like to send him in with full HP after one of my pokes has just died and immediately use Shell Smash. Then either try and sweep from there using sturdy as insurance or if they haven't done any damage again, use Shell Smash again and hope they don't have any pokemon with priority. Life Orb is sort of counter-productive when used with Sturdy and Liechi Berry gives you a better boost than both Expert Belt and LO. Its also extremely accessible due to Sturdy and the decrease in DEF and SP DEF. But like I said, you're only real weaknesses are pokemon with priority, entry hazards, or first turn status afflictions. Otherwise, after 1 or 2 Shell Smash's AND a boost from Liechi Berry, he is pretty unstoppable.