I think I would really have to throw my support behind either Weak Armor or Illusion, although Rattled is interesting too. Weak Armor is probably the best option in my opinion. It allows you to switch into a fighting move, or earthquake or something, then proceed to use the boost to attempt to sweep the foe. I think its the best risky option here because it allows you to come in on moves that don't have a huge likelihood of KOing you after rocks+assorted other hazards, but still leaves you extremely vulnerable to priority and stall that can manage to get a status effect off on you. Also taking what is probably going to be a decent sized physical hit with rocks, will leave this CAP probably to weak for another similar switch in attempt, so you only have one shot at it. I believe this risk-reward ratio is what we're looking for with a project such as this, so i think this ability should at the very least be strongly considered. Rattled pretty serves the same purpose as this, however only being able to come in on moves that are going to hit super effectively will make switching in far too dangerous, which is too much risk considering how fragile the sweeper will be even after it gets going. Illusion just sounds like a lot of fun, and with proper bluffing it could be a very high risk/reward ability. It would fit the bill for this CAP, but i think Weak Armor does a better job representing true risk to reward management. Anyway, those are the thoughts of a noob, consider them as you will.