#4 Elias
WWE enthusiasts know that Elias has the caliber to sell inside the squared circle. His time with the company has been entertaining, as Elias has given the WWE Universe quite a few hysterical moments, always with guitar in hand. His in-ring skill set and audacious mic skills make him a valued performer within the company, one who can be trusted with someone as renown as Cain Velasquez.
Avid followers of UFC will agree that Cain Velasquez has never really been a big talker. Considering the significance WWE puts on speaking, pitting Elias against Velasquez will help creative in establishing an equilibrium in this rivalry, courtesy of Elias' awe-inspiring mic skills.
Apart from this, one major reason for the company to turn to Elias as Velasquez' opponent is that the singing Superstar has a vast number of moves and will probably need them all against someone as vicious as Velasquez.
#3 Rey Mysterio
How does the prospect of a battle between two Latino Superstars Rey Mysterio and Cain Velasquez sound? Booking Velasquez against 'Mr. 619' will surely give creative a lot to work with, as both men have similar backgrounds.
WWE did something similar with Alberto Del Rio upon his debut with the company. The 'Mexican Aristocrat' was booked in a feud against Rey Mysterio simply because of their Hispanic background. Velasquez is a massive name in the world of MMA, while Rey Mysterio is a future WWE Hall of Famer. A clash between the two would certainly be eagerly anticipated by both the UFC and WWE fan bases.
Despite the size disparity, fans will believe in the match simply because Mysterio has been the underdog his entire life. As for Velasquez, it will be an honor for him to face one of the greatest stars in wrestling history.