A very easy achievement to achieve yet still 0% but a few of all players seem to have it.

If you wanna use this trick then it actually doesn't matter which kind of divisions you build or how you improve your industry that much.
Just make sure that you have enough divisions to secure your naval bases, though.

I turned historical focuses off to increase the chaos and did choose the 'Jefe máximo' focus to get the minister for the extra political power. I also avoided both civil wars. (kept the Caudillo Tensions low by focuses and always moved back to Assertive Church by Decisions)
But it should be possible even if you prefer historical focuses or to fight the civil wars.

1 - Rush down the focus tree to 'Knights of Columbus'. (It gives you a daily Democracy bonus of +0,10)

2 - Rush down the focuses below 'Ban Political Militias' until you reach 'Falangist Veterans' or 'Support Spain's Loyalists'. Choose one of them. (It doesn't matter which one)

3 - After that wait until the popularity of the Democratic party reaches 40% and until the war tension is high enough for you to justify war goals.

4 - During the wait make sure that you are able to become a Catholic state by Decisions right before you reach the 40%. (Have at least 75 political power and have Powerful Church already)

5 - When the popularity of the Democratic Party is higher than 40% and the world tension is also high enough to justify then turn to a Catholic state and choose the focus 'Catholic Politics'. Mexico will become a Democracy after that.

6 - Before this focus is finished you need to start a justification against Venezuela. As Democracy you won't be able to justify war goals so easily anymore.

7 - After 'Catholic Politics' is done choose 'Realpolitik'. After this focus is done invite Colombia to your faction and let them be conquered by Venezuela which should join the Axis sooner or later and get a lot of help from them.

8 - The achievement is done after Colombia capitulated.

I did this achievement in my first try and got a lot of help from Facist Great Britain that supported Venezuela right away.



It might be helpful if you start a justification against Brazil or another South American country with a border to Colombia, too. That way your Ally will have to fight a war on 2 fronts and capitulate sooner.
Good luck!