Trumbo finished 2-for-3 with a homer and a double before being replaced in the sixth inning, while Weeks went 1-for-2 as he continued his transition to left field for Seattle.
Collmenter needed just 18 pitches to zip through two scoreless innings -- allowing only a leadoff single to Austin Jackson -- in his first appearance of the spring, and then he threw in the bullpen in order to build up his pitch count following the outing.
"The biggest thing for me is fastball command," Collmenter said. "I threw all fastballs except for one -- I was able to get a curveball in for a strike. I just really wanted to establish the fastball, been working on it a lot."
Iwakuma looked just as sharp, requiring only 22 pitches to roll through two perfect frames. The 33-year-old got five ground balls and one fly ball against the D-backs, then went to the bullpen to toss an additional 20 pitches after being replaced.
"I felt very good on the mound today," Iwakuma said through translator Antony Suzuki. "I needed to work on a few things out of the set position, and I was able to do that in the bullpen. It was a good day."
Seattle took a 2-1 lead in the fifth when D.J. Peterson followed Weeks' homer with a double and then scored on Mike Zunino's base hit to left. Arizona tied the game in the sixth on an RBI single by Aaron Hill before both teams went to their benches in their fourth games of the spring.
RBI doubles by D-backs hopefuls Jamie Romak and Blake Lalli in the ninth gave Arizona the win.
Up next for D-backs: Cuban free-agent signee Yoan Lopez will make his D-backs debut at 1:10 p.m. MST Sunday afternoon in a split-squad game against the Giants at Salt River Fields. Fans can watch live on MLB.TV.
Up next for Mariners: Veteran left-hander J.A. Happ makes his debut as the Mariners travel to Goodyear to face the Reds on Sunday in a 1:05 p.m. PT game. Happ was acquired from Toronto in a trade for Michael Saunders in December and is expected to slide into the middle of Seattle's rotation. The game will not be televised live in Seattle, but is available on Gameday Audio and 710 ESPN Seattle radio.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.