This guy is unlike anything we've ever seen before. He is a bit of a throw-back in terms of his ring attire and wrestling style, but never has the WWE had a top, clear-cut Mexican heel. All the old Mexicans heels back in the 50s were just like him, except they wore masks.
Anyhow, he has all the tools to become a main eventer. I'm also sure WWE has big plans for him, (do I hear a match with Cena at SummerSlam?) The problem here is that WWE also has big plans for Cena (obviously), and Miz... and Dolph Ziggler as well. Smackdown was also left without a top heel. Despite his feud with Christian getting stale, could somebody please tell me why this guy was drafted?
I don't see anybody out there for him to feud with right now. He and his lackey announcer could always form a tag team and feud with Kane/Show... but I do have one idea. At least leading up until Over The Limit (and we've seen this before) he could enter a mini program with Evan Bourne, and have Bourne go over one night, have Del Rio go over another night, and then have some kind of rubber match at the ppv. Jericho has done something similar before, and Sheamus too, i think. Post Over The Limit, slowly work him into a feud with Cena. I'd sit Miz out for a month after OTL (kayfabe injuries), and have a fatal four way between Cena, Del Rio, Rey, and Truth at CP. By July, maybe someone will have turned face to work with Truth/Miz while Del Rio begins his pursuit for the title. Just my two cents, but this guy is too good NOT to include in the WWE Title picture regularly.