From ErfWiki

Proposed Canon

Natural allies (or non-capital sides) are sides in Erfworld that have no capital, no cities and no royals.^Erf-b1-p079a They do, however, have their own treasuries and can form long semi-permanent alliances, or they can sustain themselves via mining, farming, hunting, and such. Rather than using cities, they can pop more units for their side via Moneymancy ^WoT-6051503.

Known natural allies sides:

• Gobwins (seem to be natural allies to Gobwin Knob)
• Marbits (seem to be natural allies to Jetstone)
• Elves
• Witches