Okay, so I figured it out (kinda) my current way is:
First, copy the file that you want to wander into templates/gaia. Otherwise, your trainable units will wander and be uncontrollable. Then, edit the file like this:
1: Change the template at the top of the file to templates_units_fauna_wild_aggressive.
2: Add the movement speeds, armor, damage, generic names, health, vision, and all the other stats of the unit that the original template was defining.
3: Add to the Classes: Human and Organic. Add to the VisibleClasses: Melee.
4: Add what wowgetoffyourcellphone posted above, right above your Promotion data. Add Loot and ResourceGatherer disable=“”.
If you want the unit to be nonviolent, make the template be templates_units_fauna_wild_passive. Also, make sure you say wild and not hunt, or food can be gathered from downed AI soldiers.