So basically make the post have HEAVY emphasis on the breast cancer donation and just be like "Look how much money these smash players have all donated for breast cancer!" or something, and then ask them to donate and when you link to the donation page make sure its the Melee one. I'm not too good on wording these things, but basically we need to get them to feel good about donating to breast cancer and giving their money in support of melee.
How do we do this?
Unfortunately, I think that would backfire; personally I think redditors tend to be very cynical and suspicious by nature, and they're usually vicious against any attempts at manipulation if they pick up on it (even though we see them being fooled all the time)... I feel like if anything, there's going to be more than one guy who will decide to investigate and even find this thread.
I think the best chance would be to completely remove melee from the title and just throw it up as a "donate for breast cancer and and get your favorite game on EVO!". It's a gamble, but I feel (as was stated earlier) that without trying to put a spin on it, melee will probably have the most supporters in a large mass of gamers anyway.
And with one more note, I think we should not be thinking with the mentality of sniping (or being sniped), because it is much better to simply keep throwing in the funds instead of deciding on a "safe" goal.
In the end, I'm a fan of both games. Melee's carried me and my close friends through our spare time during the entirety of college, and I've always thought Skullgirls was an amazing attempt by a Western indie developer to introduce a respectable fighting game. I know that the smash bros community gets a lot of flak for being "pretty bad" (putting it nicely), so let's use this opportunity to show them wrong! I think regardless of who wins, the behavior of both communities will definitely be key. There's little point in winning but looking like huge jerks!