I'm an avid pokemon fan, especially of the older gameboy and gameboy advance era games.  Many people my age are this ay, and when I bring my gameboy sp with me in public it very often gets noticed and appreciated.  With the popularity of pokemon go, and the amount of people who point out my old games, i think there are many people who want to play the old games but don't have much oppurtunity to do so.

My cross-pollination idea is to essentially create an app like pokemon go but for old pokemon games. In the games you fight trainers known as gym leaders, the on trait all gym leaders share is that their pokemon all share one type.  My app would allow people to essentially make their own gyms.  The basic idea is a user who wants to make a gym would use a map to pick a spot to place their gym, then input their team they plan on using, when their gym will be "open", and what generation of pokemon they will be battling on.  Then any user looking for gyms of that generation to battle could see this gym and the date/time it will be there, allowing easy facilation of battling.

The tech stack would include google maps api and possibly google directions api to get a user to a gym.  There isnt an offical pokemon api but there are several decent fan ones.