EUR / MXN is very exotic pair, in fact, as well as the bundle USD / RUB. It is common only in a narrow circle, since the currency quoted is Mexican peso. Mexican peso is the national currency of Mexico. Although it is on the list of freely convertible currencies, there is no outspread outside Mexico, and it is unlikely to be widely used. The EUR / MXN currency pair as a whole is classified as low-liquid - you will not earn much on it, and it is extremely difficult to forecast its rate - this requires a lot of experience. You can understand this by looking at the comparison of this pair with the bundle EUR / USD.