I think it depends on the "shard". Every "shard" seem to have a few gold cards that are 3-color, but I'm guessing part of that was the mandate. The wGr shard (Naya), which the Nacatle belong to, seem to have a number of green cards that benefit from white and red. The Wild Necatle being an example, but there is also Naya Battlemage, a green creature with 2 abilities requiring red and white mana respectfully. Naya also appears to have some serious beef, with Qasali Ambusher and Wolly Thoctar, both more traditional gold cards.