Big cities have varied and growing public transportation systems:

Metro:

CDMX and Monterrey

Metrobus, Macrobus or Mexibus:

CDMX, Guadalajara and Toluca

Bus and minibus:

Almost in all cities with cash

Light rail and cable bus:

Only avalible in CDMX and metropolitan areas

Public bicycles:

Ecobici (CDMX) and MiBici (Guadalajara)