I agree, you can roleplay Pokemon relatively easily with a simple but fun premise. I imagine animes with large worlds that aren't all explored in the show would be quite interesting to roleplay, lorewise, as you have the freedom to make up some of your own ideas with not too many barriers. The alchemist world of Full Metal Alchemist would probably be perfect for that. I imagine you can do lots of cool stuff with auto-mechanics (possibly testing the limits auto-mechanics), but also with lots of different cool types of alchemy, you can invent while being able to still have an interesting and exciting roleplay outside Amestris outside the main city area. I would personally love to roleplay inside the FMA universe possibly in Xing since it wasn't explored in the Anime that much. I imagine some kingdom conflict might be very cool.