Hello everyone and welcome to my 9th analysis, this time featuring Petro Loa.
Petro's a good Nature attacker and a good Nature monster in general. He has access to Dark attacks, which is a good thing since he can hit Nature monsters with them unresisted and also have power vs. Earth monsters. Having a move that gives Precision+Double Damage is very good but it also makes its trait kind of a waste, plus Petro doesn't have a deny move which is a negative.

-Mouths to Feed
-Loa's Will
-Butia Yatai Leaves/Guarana Leaves
Runes: 2 Strength 1 Speed

Mouths to Feed is a 50 Base Power unresisted AOE, a godsend for any attacker. Zompafuosso does hefty damage and is pseudo-unresisted. Loa's Will gives him the precious Double Damage+Precision. Lastly, Butia Yatai Leaves has even higher damage than Zompafuosso and and it's effective against any non-Nature monster, or Guarana Leaves rids him of annoying status and heals him to a great extent. 2 Strength runes give him damage, and even among an element poor on deny options, 1 Speed is necessary later on.

Teammates: Kiridar can greatly increase the power of Butia Yatai Leaves. A denier is a must since he needs one free turn after using Loa's Will to wipe out the enemy in one hit.

Countering Petro Loa: Don't let him use Loa's Will, if he manages to use it, make sure you deny him afterwards. Timerion's Space-Time can protect you from his huge AOE strike.