Well this is one good question I have to admit. I would choose Wrestlemania 26 just like yours. Opponent was Shawn Michaels nonetheless.
How do I change the story? : Well, I would make Shawn Michaels lose the Royal Rumble 2010 and ended up in Shawn Michaels being desperate to get his hands on The Undetaker and The Undertaker refused to accept Shawn Michaels's challenge until Shawn Michaels proved himself to be worthy enough to face him for the 2nd time at Wrestlemania 26. Then Shawn Michaels managed to qualify for the WWE Championship Elimination Chamber and won the WWE Championship after 3 Sweet Chin Music to Triple H to win the match.
And then Shawn Michaels appears to the World Heavyweight Championship Elimination Chamber match and superkicked Chris Jericho instead and Undertaker pin Jericho to win the match. Then on the following Raw, Shawn Michaels who is the new WWE Champion called out to The Undertaker demanding to a match at Wrestlemania 26. Undertaker looked at Shawn Michaels and accepted the challenge under three conditions.
The first is that Shawn Michaels need to defend his WWE Championship. The second is if Shawn Michaels lose, he will be forced to retire and the last condition is the match would be a Hell in a Cell match. Shawn Michaels accepted the challenge but he has two conditions, he want Undertaker's World Heavyweight Championship to be on the line as well making this match a Undisputed Championship Hell in a Cell match and if Undertaker loses, Undertaker's career is over.
Change of match: The match is now a WWE Championship and World Heavyweight Champion unification match and it will take place inside Hell in a Cell match. Shawn Michaels and Undertaker's careers will be at stake, making this match a Title/Career vs Title/Career match. How The Streak ends: The match has been going up and down and in the final moments of the match which the match has been going on and off for the last 45 minutes making this match the longest Hell in a Cell match in WWE History, Shawn Michaels is about to set Undertaker up for the Sweet Chin Music but Undertaker countered it to a Chokeslam through a table.
Undertaker has given the signal that the match is about to end but he stopped and looked at Shawn Michaels who is pulling himself up with the help of the ropes. Undertaker tried to do the SCM but Shawn Michaels countered it to his SCM and Shawn Michaels pinned Undertaker but Taker kicks out at 2 and 3/4. Undertaker sit up and gave Michaels a Tombstone Piledriver but didn't go for the pin.
Instead he brought a steel step in and gave Michaels the R.I.P sign and gave the final Tombstone Piledriver to Shawn Michaels but shocking turn of events when Shawn Michaels kicked out at the final second. Undertaker was shocked so as the crowd at Arizona. Undertaker then gave the ultimate sign and the lights in the arena began to flicker.
Undertaker picked up Shawn Michaels for the Tombstone but Shawn Michaels countered and threw a steel chair at Undertaker while giving him a SCM and Shawn Michaels pinned Undertaker to end the streak and unified both the WWE Championship and the World Heavyweight Championship at the expense of Undertaker's career and streak. Number of Finishers that Undertaker uses: Tombstone Piledriver : 4 Last Ride: 2 Chokeslam: 3 Hell's Gate: 1 Triangle Choke: 1 Number of Finisher that Shawn Michaels uses: Sweet Chin Music: 5 Elbow Drop: 3 Figure Four Leg Lock: 2 BQ: Yes. :D BQ2: Technically, Undertaker was beatable back then as WWE has no plans to make him undefeated in the first place so somewhat they did maintain his undefeated record and volia, it became a Wrestlemania tradition.
I would've had his streak end at Wrestlemania 26. I would've done the same thing as you and have Michaels win the Royal Rumble. Then keep Undertaker the champion.
Then at the Elimination Chamber PPV, Michaels comes into the Elimination Chamber and after Undertaker had won the match, Michaels comes into the Chamber and gives a Sweet Chin Music to him. Then Michaels takes the World Heavyweight Championship and holds it above his head (in a taunt pose). Then Shawn leaves the Chamber, goes up the ramp, and looks back, and raises his arm (like Undertaker does).
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.