The Rusty Gulch is a map in the 2-Player Battle mode of Pikmin 2. It is constructed out of rusty metal pathways held by large pillars. Certain spots have odd colored "sand", and the entire stage is floating over a bottomless void in which Pikmin die when thrown, and may be home to a Gatling Groink. One of the layouts that the stage can have bears great resemblance to that of Subterranean Complex, sublevel 5 and Dream Den, sublevel 4, featuring multiple ramps with a high area at the center.
Gatling Groink strategies
One very interesting strategy involving the Gatling Groinks in this area is to actually have a Gatling Groink guard your base and marble from opponents. First, find a Gatling Groink, preferably close to your base. "Kill" it, then have your Pikmin start bringing it back to your Onion. Right before they bring it to the Onion, call them back. After a bit, the Groink will fully regenerate in your base. This is a good strategy if you don't play by getting yellow marbles, but remember the Groink will attack anyone's Pikmin, so be careful when carrying items back to your base.
If you do play by getting yellow marbles, another way is to intercept the opponent whilst carrying a Gatling Groink near their base, and make sure the Groink revives. This means that you can gather yellow marbles faster while the opponent fumbles around with the Gatling Groink. This strategy is more effective for getting yellow marbles and making your opponent slow down.