Across the Sea of Cortez on the Baja side, the Sardina rules supreme as baitfish of choice along with Cabillitos, anchovies and mackeral. I would bet that they are also to be found in big numbers on the mainland Pacific side.
The sardinas can be anything from an inch up to 5 or 6 depending on time of year. When I was there in the late fall they were small and we fished two inch olive/white clousers for 20lb yellowfin
Cabillito is a deeper bodied "Big-Eye" baitfish 5 to 7 inches or bigger. Some type of bunker immitation would probably fit the bill.
Roosters can be notoriously finicky - the "Pacific answer to Permit" - lots of excited follows but few conections and lots of bad language
Grant Hartman of Baja Anglers favors a one inch edgewater popper (master blaster?) - top half black, bottom half white with a red face and the biggest stick-on eyes you can find. The tail is a mix of white and brown bucktail with a few strands of flash. He's taken many world records with this fly.