Well, with the IWC its pretty difficult to plan debuts that are special and meaningful. However the surprise debuts of the past era(s) just had a lot more "oomph" behind them than the usually lame character promos leading up to a debut.
Just hearing a cool new theme song and than seeing a new wrestler walk out surprising the audience is just more powerful and memorable than some lame built-up debut against some random jobber.
Probably debut as a mysterious (unseen) guy who abducts Vince McMahon and holds his family to ransom by sending videos to Raw of him tied up. It is eventually revealed he is Triple H's cousin. Maybe too TV-14 soap opera though.
I would give him the Stone Cold debut style. First he would be given a decent gimmick for starters. Example Ringmaster. Then from their give him a feud a few months later. Have him win some kind of tournament during the middle of the year. Sooner or later put him in a feud with a veteran. While he gains mega fans from his outstanding work. Give him a title shot in the next year, but not have him win it so fast. Give him the title a year later.
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Main Roster Divas: Paige and AJ Lee
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[x] Wade Barrett wins any championship [x] Dean Ambrose Debuts
 Damien Sandow wins any championship
 WHC and WWE Championship are unified
 Christian wins another main event title [x] Chris Jericho returns [x] WWE Championship design is changed [x] CM Punk vs The Rock