Note: Well, I don't know very good how do this because I don't have the original map without the darkness, but I'll do my best putting a tutorial with photos.
That men it's a trainer
|Leonard||Geodude lv 12
Machop lv 12
Let's go left and up
We're lucky, we found a potion, then, let's go back to the beginning and let's go to right side
A trainer !
|Wayne||x2 Geodude lv 8
Geodude lv 9
Now let's go down
Another pokeball ! We found one Revive
Let's go back to the middle where we find "Wayne" trainer
and let's go right side from Wayne
We found a trainer and a stair