#9 Tommaso Ciampa
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Somehow, someway, Tommaso Ciampa will retain his NXT Championship tomorrow night. WWE would be foolish not to have the best heel in the business show up in the Royal Rumble the next night. Since he's the NXT Champion, we can expect him to appear just like Andrade "Cien" Almas did last year.
With Aleister Black likely in the Rumble as well, there would be a natural carry over feud from NXT, to advertise the yellow brand on one of WWE's biggest stages.
Tommaso Ciampa would make for a fun presence in the Rumble regardless. Seeing interactions with pure babyfaces like John Cena or Mustafa Ali would make for some memorable content and Ciampa can scheme the most devious ways to keep himself alive for as long as possible.
The man who should be the eventual winner, Seth Rollins, would get a tremendous pop for eliminating him, as well, which alone makes his appearance worth it.