Wallisch, who lives in Park City, finished second with a 92.25, while Brown was third with a 91.
"I've been emulating them ever since I was little," Goepper said. "To be skiing with them now is incredible."
A third-year student at Windells Academy in Oregon, which is essentially a winter school, Goepper grew up 10 minutes from Perfect North Slopes in Indiana.
"He was always jumping around and spinning around and everything before he was even skiing," Goepper's father, Chris, said. "Once he got into the terrain park, it was all over."
By finishing second Sunday, Wallisch won the Dew Cup as the season points championship, following wins at earlier stops in Breckenridge, Colo., and Killington, Vt.
Wallisch missed most of last season with a shoulder injury, and missed a chance to become the winningest slopestyle skier in his adopted home state.
"Missing skiing during the middle of the year, the competitive season, is so hard," Wallisch said. "It's hard for me to be off my skis, I love it so much. It's awesome to come back and do so well this year."
But he acknowledged that he doubted his final run would be enough to topGoepper.
"The firsts I've been getting have been really good," he said, "but it's almost too good."
The man from the posters said Goepper, who landed a switch double-cork 1440 on the final jump, is staking his claim to a piece of the sport.
"He'll definitely be up there all the time, one of the best for a while," Wallisch said. "I'm definitely trying to get him while I can, and being able to beat him these first couple contests this year is good."
Goepper finished in the top three at each Dew Tour stop this year and earned silver at X Games.
"I just wanted to come in here and stomp my run and get it clean and get a good score," he said. "That's what I wanted to do, and I ended up winning."
Storylines Rookie wins Dew Tour stop
R Nick Goepper scores a 95 to win his first Dew Tour stop.
• Park City skier Tom Wallisch, 24, was denied the chance to become the first person to sweep every stop of the Winter Dew Tour.
• Wallisch becomes the first athlete to win both X Games and the Dew Cup in the same season.
• In women's ski slopestyle, Park City's Devin Logan finishes third to complement her win the night before in the superpipe.
Sunday's Dew Tour results
Men's ski slopestyle final
1. Nick Goepper, Lawrenceburg, Ind., 95
2. Tom Wallisch, Park City, 92.25
3. Bobby Brown, Breckenridge, Colo., 91
Women's ski slopestyle final
1. Kaya Turski, Montreal, Quebec, 93.75
2. Anna Segal, Melbourne, Australia, 90.75
3. Devin Logan, Park City, 89
Men's snowboard slopestyle final
1. Sebastien Toutant, L'assomption, Quebec, 94.5
2. Dash Kamp, Sandpoint, Idaho, 83.5
3. Spencer Link, Corona, Calif., 77.75
Women's snowboard slopestyle final
1. Spencer O'Briend, Coutenay, B.C., 94.5
2. Enni Rukajarvi, Kuusamo, Finland, 86.5
3. Joanna Dzierzawski, South Lake Tahoe, Calif., 80.25