Originally Posted by
Storm Trooper
They put everyone on the card because Wrestlemania is the biggest show if the year with the biggest gate, the most PPV buys, and as such the biggest payday of the year. If they hold people out of it, morale in the locker room would go down big-time due to being left out of the biggest payout of the year. How would you feel if you went to your work, and the boss told you that everyone working on a specific day was going to be given the biggest payday of the year, but not you because he just didn't want you getting that. Now you feel like a loser, your peers know your boss thinks less of you, etc.
The Battle Royale is a much better alternative to what they did in years past which was a random massive tag match (hell they did a 7 on 7 match at one point), or a lumberjack match. Plus it CAN be used to get some momentum rolling for whoever wins. Baron Corbin used it to launch his debut, Cesaro used it to launch a singles push (albeit one they held back, but still), hell even Mojo used it for a few months.
As for the match itself, it's next to impossible to pick, but I wouldn't be surprised if it's either Woken Matt Hardy, Brother Nero, or Bray Wyatt post-Reincarnation.