Cascade Tunnel

You decide to continue on your Pokemon journey on this Island. After leaving the town you entered a dark woods, and eventually the road led right into a dark tunnel known as the Cascade Tunnel. The tunnel is supposed to hold a large amount of Pokemon, and it is rumored to also have a Gym hidden inside it's depth.

You enter the tunnel and it is pitch dark. Accept for a few rays of sun coming in through cracks in the sides and ceiling. Walking through the first part of the cave you across (pick 5, they may be more than one of any Pokemon)