Earlier on Saturday, another Mariners split squad played to a 5-5 tie with the Dodgers.
Ian Kennedy, the D-backs' Opening Day starter, gave up four earned runs in his three innings of work to take the loss.
"This was just kind of getting your work in, second outing," Kennedy said.
Montero, the 22-year-old catcher acquired from the Yankees in the offseason for right-hander Michael Pineda, delivered the first blow for the Mariners in the first, whacking a two-run double off the wall just to the right of dead center field.
Murenori Kawasaki, who led off the game with a single and went 3-for-5 with three RBIs on the night, drove home two more in the second to give the Mariners a 4-0 advantage.
The Mariners added on in the seventh on an RBI single by Brendan Ryan, driving home Darren Ford after he'd blazed around the bases for a triple. Ryan came home on a sacrifice fly by to make it a 6-0 game, and the Mariners added another in the seventh on a Kawasaki RBI single.
Ramirez was relieved by Danny Hultzen, the team's first-round pick (No. 2 overall) in the 2011 First-Year Player Draft, who pitched two innings, getting out of a jam in the fifth. Taijuan Walker, a 19-year-old fireballer, followed with a shutout inning that included a strikeout and left-hander James Paxton gave up a run in the seventh, hitting a batter, walking one and pushing the run across on a wild pitch.
"I thought they all handled themselves well out there," Wedge said. "It was great experience for all of them. I liked their stuff, I liked the way the ball came out of their hand and the life it had around the plate. This was more about breaking them in ... giving them experience out here, in a Spring Training, big league game and everything that goes with that."
D-backs outfield prospect Adam Eaton scored Arizona's run three batters after being struck by a Paxton pitch.
Up next for Mariners:
Felix Hernandez makes his second Cactus League start, facing the Giants in a 1:05 p.m. PT game at Scottsdale, Ariz., on Sunday. Hernandez went three scoreless innings vs. the Reds on Tuesday as he prepares to be the Opening Day starter March 28 in Tokyo vs. the A's. Tom Wilhelmsen, Shawn Kelley, Oliver Perez, Cesar Jimenez and Steve Delabar are scheduled to pitch in relief.