1) Walk to straight up to Mephisto (face to face) and tell him "F**K YOU!!" while in Mephisto's realm...
Wolverine is the only one who would use that kind of language. If you don't mean literally, everyone of them would stand up to Mephisto even in his own realm.
2) Seduce a hot chick (just some normal hot human babe)...
Wolverine has a higher level of pheromones that make him more alluring to woman; but Bruce has also got pick up skills and cash to boot.
Of course, Superman or Thor could simply say " Hi, I'm Superman" and "Greetings, I'm Thor" but they wouldn't do that.
3) Seduce She Hulk...
She-Hulk is a tramp who will sleep with anybody who can press more than 80 tonnes: That leaves just Supes and Thor
4) Talk the President out of a massive increase in taxes...
Nobody - that's like talking Death out of death.
5) Convince the peoples' of the Middle East to hand over Bin Laden willingly..
Only Superman.
6) Talk Captain America into getting a lap dance at a "butt naked" club...
Only Thor could, but he wouldn't. Wolverine would try.
7) Beat Lex Luthor at a game of chess...
Cap or Batman - not as smart in most ways but better strategists.
8) Successful resist being seduced by Wonder Woman...
WHY WOULD ANYONE DO THAT?