I haven't done any 'runs' yet, so I'm not sure whether this would be doable and stuff, but what about a "Pokémon Lottery Run"? The idea is that you would get access to a new evolution line with every new area. Using a Pokémon randomizer on the internet, you generate a random Pokémon right after you enter a new area; the species you get and the rest of its evolution line are now unlocked and can be used from now on. This way you unlock more and more Pokémon as you progress in the game, and as the battles become tougher.
The specifics can vary depending on how hard you want the run to be:
- In order to get started, you want to have a number of rolls on the randomizer at the very beginning of the run. (I'd say somewhere between 5 and 30 rolls depending on what you choose to do with the other specifics below and on how hard you want to make it for yourself).
- You could allow yourself to trade with online players (so that you have access to rare unlocked Pokémon at any point in the game) or you could not, in which case I recommend increasing the number of rolls you get at the beginning of the run (because otherwise you might not even be able to get going properly).
- If you don't draw any starter at the beginning, it's up to you whether you allow yourself to use a starter. If you do draw one or more starters, you have to choose between those you got.
- Every time you draw a Pokémon you had already unlocked at another location, you could either allow yourself to try again or you could decide not to.
So, let me know what you guys think of the idea!