The overall strengths of this team
1. Driving ability and foul shots: Wall and Currie are above average at getting to the foul line and this can compensate for the team's lack of a true pure NBA range shooter.
2. Rebounding: Nene will be a space eater and grab many boards. Langhorne also has a knack of getting boards, often when I don't think she'll get them. Even Wall can do this at a good rate.
Weaknesses
1. No one single player is that combo forward type who can defend on the perimeter and the post - I feel that the best mixed teams will have players who can defend both post and perimeter players. Those combo forwards like a Lamar Odom, or an Antawn Jamison could be ultized very well in a 3x3 situation. However, we have two players that are true posts here in Nene and Lang, so I would assume that Lang will have to do more perimeter defense than she'd like to in a 3x3 situation.
2. Three point shooting and long range shooting - With no above average three point shooter on either team, except maybe Natalie Novosel for the Mystics and the newly signed Martell Webster for the Wizards, this is a problem, especially if this team is losing by a decent margin and needs some threes to close the gap sooner. However, the driving ability of Wall and Currie may compensate for this weakness.
John Wall, G, Wizards - As the star of the Washington Wizards, in many ways, he's here by default. Wall in just two NBA seasons has already shown to be one of the top assist men in the NBA, and that's considering that for most of those two years, he didn't even have that much help with shooters, and dealing with some goofier characters. Bullets Forever's Mike Prada had a season long "missed assist tracker" to show how many potential assists Wall lost because of his teammates missing shots.
As for his own scoring abilities, John is really good at driving to the bucket and has a very high rate of free throws, which will help compensate for his lack of an elite far range pull up shot (for the WNBA, think Sue Bird, or for the NBA, Steve Nash) or a three point shot (Nash again is great at the three), where he averaged under 10% on in the 2011-2012 season. Along with Nene as a pick and roll partner and with fewer players as well as smaller female players packing the paint to stop a big NBA point guard (keep in mind, his 6'4" height is basically a WNBA center's height), Wall has some great potential to score many buckets even without a great far range jumpshot. Lastly, on defense, while Wall can definitely steal the ball very easily given his long wingspan, he is also a pretty good rebounder and shot blocker for his position, so he can also be a wing defender whenever Mo Currie is the sole female player on the court.
Nene, C, Wizards - Most Wizards fans were pretty stoked about Nene coming to DC, purely from a basketball standpoint, though he does have a long contract that will pay him well over eight digits a year over the next four years. However, let's think about the now. Nene is a great pick and roll player on both offense and defense and should open up those driving lanes for Wall and Currie who are the perimeter players for this team. In addition, for the few games that I've seen him play, Nene is also a good passer for his position and won't hesitate to kick it out to players for a shot or an open layup, unlike his predecessor, JaVale McGee.
Nene has been criticized for not being as big of a rebounder for his size, but this is a 3x3 competition, so I don't anticipate seeing that kind of trouble. Lastly, Nene has a decent midrange shot, where he can take and make that 17-18 foot shoot with regularity.
Monique Currie, G/F, Mystics - Mo is the team's best all around perimeter/wing player for the Mystics. She is a decent scorer, and like Wall, she has a pretty good free throw rate, and with Nene, Lang, and/or even Wall setting screens for her to drive, this is how she too can score a lot of buckets. Mo isn't the best three point shooter in the world by any means, but she can get in a rhythm and score pretty quickly as well. When she is with Wall on the court, she could take advantage of open looks as a catch and shoot player when John is driving to the bucket and meeting defenders, and she can get hot from three. Maybe Wall and/or Nene can make that happen.
Like most of these mixed NBA/WNBA 3x3 teams, the WNBA player may be in a bad position defensively if she is a sub 5'10" ish guard and in almost all cases, if she is a post player and is put on an NBA player. In Currie's situation, this applies for the former, but when she is the only female on the court, she's with Wall and Nene who can definitely compensate for her.
Crystal Langhorne, F, Mystics - Lang is the best player on the Mystics and is here by default in many ways like Wall. She is arguably one of the best post players on offense in the WNBA, and knows how to get buckets.
The one problem I see with Lang on this team is that she is a true post player, and is slightly undersized at her natural PF position for the WNBA. In a man to man defense situation, she will almost definitely be shorter than most of the NBA players who she'd be against on a mixed team. Fortunately, if she is playing on the court with Nene and Wall, they could compensate for her defensive deficiencies since Wall is blazing fast, and Nene has a general knack to be at the right place at the right time on defense, not to mention both players are taller and stronger than her. In addition, Langhorne also has a good midrange shot up to that 20 foot range even where she is able to make that shot consistently, and this can help compensate for her lack in size if she is really overmatched.