[Endoperez]

Ancient Treants already exist in the Treelords, they could use a boost, like becoming more mobile, but they're unique so they wouldn't solve the problem.

Elemental Princes and/or Princesses would work, but obviously they wouldn't have random paths.

Legendary animals would be nice, especially if they were also available from Transformation. Great Bulls, Sons of Fenrer, perhaps Even Greater Eagles (Storm Birds?), Great Bears similar to Bogarus summon...
They wouldn't be SCs if they were normal animals, but if they were embodiments of the elements (similar to Fall Bears, Summer Lions etc) they could be very powerful indeed. Ethereal, great stats, probably immunity to one and resistance to other element(s)... There could be more than the four basic ones, for magic combinations (e.g. Nature /Blood). They could even be Nature summons, if the emphasis is on their animal part instead of their elemental part.