Well we know they're well armed with the 50 calibur sniper rifles, the AK47's and the AR15's and now we learn, the gernades that our government gave them. For all we know, they may have given them shoulder fired missles too.
Unfortunately they are well trained. The core are former Mexican special forces/paramilitary who got turned (due to the money), and the rest are well trained. They are well equipped, with the shock troops being very well equipped. They are also well connected, indicating that one can never really know whether you are talking to a legit cop (as an example) or a cartel member who also happens to be a cop. Furthermore, with the various internal fights between different cartels (and cartel groupings), they tend to have a lot of practice. In conclusion, while they are far from invincible I would still say they are good fighters. Ranging from good to really good.