There are two Pancho's in Mazatlan, one is on the beach in the Gold Zone and the other is about a mile north, across from the Pueblo Bonita Resort. Both are well staffed, clean, and have very good breakfasts.
I prefer the one on the beach for breakfast because of the ocean view. You can either sit outside for an open air view of the beach or in the enclosed dining area upstairs with the same ocean view. There are about 8 specials for breakfast - the standard breakfast is always good (eggs, bacon, ham, etc.) but I prefer the Machaca with chiqutas. Pancho's on the beach is usually very crowded, so be prepared to wait for breakfast with a view.