There aren't too many stipulations on the WrestleMania matches this year. In fact, as of right now there aren't any. Some matches have more than two people in them, but they haven't added anything to them to make them special. A potential stipulation for Cena/Wyatt could be a Street Fight or a No DQ type of match. The reason that works is because Wyatt could have the help of Rowan and Harper. It makes Cena a bit of an underdog. However, it could lead to more negativity from fans that are sick of Cena overcoming the odds to win or if he were to lose it could be because of the interference. The right finish would be something where it seems like Rowan and Harper would help Wyatt win, but Cena finds a way to kick out initially while taking care of them. Then Wyatt comes back, hits his finisher and wins. Most likely they won't add a stipulation because the following PPV is called Extreme Rules, which will be loaded with stipulations, and if they do a rematch there then they're saving the "extracurricular activities" for that show. It makes sense.