Here's a map. (
http://img.photobucket.com/albums/v303/ttchan_2004/lostcave.png)
I made it a few months ago. You now need the upper one. Be sure to visit the another cave. You can catch #109 Gible there. The entrance is directly under the bridge.
2007-06-16 08:18:29 補充:
People you have accompanied will be your partners in the battle tower if you have chosen double battle mode.Refer to this page for details:
http://serebii.net/diamondpearl/tower.shtml