Gomes was acquired along with cash considerations from the Reds on Tuesday in exchange for two Minor Leaguers: outfielder Bill Rhinehart and left-hander Chris Manno.
Gomes, 30, was hitting .211 with 11 home runs and 31 RBIs with Cincinnati. His best season came last year, when he drove in a career-high 86 runs for the Reds.
Gomes is viewed as a right-handed power hitter off the bench. He will also platoon with Laynce Nix in left field, as he has a career .281 batting average against left-handers.
He was not in the starting lineup on Wednesday against the Marlins but is expected to play on Thursday.
"I'm willing to do whatever it takes. I told [manager Davey Johnson] that I could play left, I could play right. I'm comfortable doing everything," Gomes said. "I just left the door open to him and let him know that I'm ready when my number is called. Whatever he has planned for me, I'm all right with."
Gomes can become a free agent after the season, but he said that he wants to play for Washington past 2011. He also wants to show general manager Mike Rizzo that he made the right deal when acquiring his services.
"When you have a GM giving up his prospects for you, it opens up your eyes. You don't want to bum him out, by any means," Gomes said. "I'm over here to play, to prove myself, to prove him right."
As for Stairs, he hit .154 with two RBIs in 56 games this season. He really didn't receive any significant amount of playing time until Johnson took over as manager in late June.
Johnson had hoped that Stairs would be his No. 1 left-handed hitter off the bench, but according to the skipper, Stairs has had one bag packed for quite some time.
"To get him off to a good start, it would have been better if he had a lot of playing time leading up to the season to keep him sharp, and he never really got sharp," Johnson said. "He didn't have the kind of production that he wanted or that the organization wanted."
The Nationals have 10 days to trade Stairs, reassign him to the Minor Leagues or release him.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.