Suadero is the traditional name in Mexico. Elsewhere, butchers sell the same piece — or a close cousin — under a different name.
Suadero, the thin rose meat, sits just ahead of the flank; falda is the most common Mexican substitute when suadero is unavailable.
Same area of the rib cage. Flecha is sold bone-in for the grill; suadero is the boneless meat from there, confited for tacos.
Both are thin abdominal-wall cuts with a layer of fat through them; vacío is the Argentine parrilla analogue to the Mexican taquería cut.
Brisket is the usual North American stand-in for suadero in tacos — a fattier, coarser grain, but it confits and shreds the same way.