Where is Donkey Mong?

Solution 1:

In the SW corner of Eridium Blight, stay to the right after passing through the gate. Donkey Mong has a chance of spawning here with or without clearing the area. If you don't see him, try clearing the bullymongs in the area. King Mong and Donkey Mong can spawn together, they do however seem to share spawn locations.

Video by GameFront:

Solution 2:

Actually, I found him more frequently if you head a little further down the road. Essentially, in between where this video recommends and where you find Mal.

Solution 3:

Location given above is correct. However, based on personal experience, both King Mong and Donkey Mong can spawn repeatedly and spawn together. King Mong spawns in at least two places: just over the Hyperion Gate and in the SW corner of the map by the exit. He spawns 3 out of 5 times for me. Donkey Mong spawns due west of the Hyperion Gate out of the cliffside. He generally spawns 1 out of 5 times in my experience.