Sylvan Stone  

Yes, every PT member wanting to do Bionic Bug will need one stone, which they will trade to the NPC to get the key item needed to enter the BC. Also note that you can't take any shortcuts (i.e. warps from moblin NPCs) to get to the BC once you have this key item, or you will lose it. You have to get there the annoying way that involves getting people through Newton and back to Oldton on top of ledges, have 3 people hit 3 different switches, and have everyone run across the ledge really quick before it drops again. Little tip: if you make sure that the WHM at least gets across, then anyone who doesn't make it can die under the ledge and the WHM can tractor them up and R3 them.

Also, you can only go into the BC once every 5 days. That is to say, if you lose, you're out of luck for 5 days. Once you've done the BC and used up the key item (whether through a win or loss), you must wait 5 days to turn in another stone for another key item.