What pokemon do you want to get future regional forms? If you need a basis, for a region based on say, greece?
This is a tricky question to answer, because yeah, it really does kinda depend on the region. To my mind, the best thing about regional forms is that they illustrate the region’s identity and culture, or the way Pokémon have adapted to the particular challenges of living there. There are no Pokémon that I think should get regional forms, because that’s the opposite of how I think about the question. But then again, despite being an archaeologist who works in Greece, I’ve also never been enthusiastic about the idea of a Pokémon region based on Greece, either; I just think there are other choices that would be more interesting. When people ask, I usually say that I’d like a region based on India. There are a few obvious choices for regional variants there that could incorporate references to Indian history and culture into their designs, although I don’t have any specific ideas for how to do that off the top of my head: Arbok, because cobras are Indian. Copperajah, because elephants are Indian. Medicham, because Buddhism started in India. Raikou, because tigers are Indian (and we may as well drag Suicune and Entei into it). Machamp, because divine beings in Indian art are so often human-shaped with extra pairs of arms. Miltank, because cows are symbolically important in Hinduism. Do something with Claydol that uses motifs from the Bronze Age Indus Valley civilisation. You get the idea.