I support this idea, however I think it would be better to have guards outside the bridge, or make it so it is "Under construction: until the Elite 4 is beaten for the first time. Otherwise like others have said, near noobs would be battling a LV.34 trainer. The purpose for the bridge would be simply to save time moving between the cave and the poke centre whilst having to go through the water and encounter at least 2 pokemon. That or you could always cut a section out of the fence so people could exit the water there.