The Master Stinger is a supporting character in Mario Golf: Super Rush. He is a hooded Koopa Troopa who appears near the start of Adventure Mode, encountered just before the player advances to Balmy Dunes. He teaches the player how to utilize their energy to perform Special Shots, as well as a Stinger Shot.
Just before the player leaves Bonny Greens, they may find Master Stinger in the Practice Area, next to a golf cart and firewood. He offers to teach the player about energy, and prompts a tutorial. He first teaches them how to hit their ball onto an island across the water by shooting a Stinger Shot at low trajectory to skim it across. He supplies the player with his Green Shell 3 Wood, challenging them to hit three of ten shots onto specific portions of the island.
Once this is accomplished, Master Stinger moves on to using a Special Shot, explaining that they can be purchased with coins. He instructs them to use one directly toward a large rock obstructing the island. Doing this correctly destroys the rock and completes the training. Afterward, Master Stinger reminds the player to use their energy in this manner, pressing when the energy gauge is full to perform a Special Shot. From this point on, the player is able to use Special Shots. Additionally, Master Stinger provides them with the club used during the lesson for their own use.