This is something I wrote a while ago (read: a couple years back) and ended up forgetting about soon after. I got pretty far in, as far as how basically every single thing works...except, well, actual gameplay.
There really isn't very much to it at all. You're brought up with a short introductory screen asking if you wanna load a pokemon or start with a new one. After making your selection, you're brought to a rather Tiny Chao Garden-like interface where you spend money to buy berries that increase your Pokemon's stats. By itself, it's extremely boring, especially since the only way you can gain more money is via pressing the up key. (it was a debug feature I left in since there's no other way of getting money)
However, the actual development process itself is extremely open ended. The brp file for Pikachu is actually an ini file that's fully commented telling you how to add more pokemon of your own. There's files for Bulbasaur and Eevee too, but I never got around to adding their sprites, nor do I know if the files themselves are really worked upon.
There's no minigames to speak of, nor is there any sort of purpose for raising a Pokemon in this way. Included with the boring way the game is played, one might wonder why anyone would download it? Well, included with it is the source. It's in MMF2 format, sadly, but if they want, anyone building a pokemon game of their own is more then free to take the source, tinker with it as they see fit and include as a real part of their game. One could even expand upon it and make the breeder into a game all on it's own. It's an open source, free to use program. You don't even need to give any credit; I made this in roughly 2 weeks, if even that, back when I started it.The source is fully commented and explains very clearly how everything works, though it still assumes you're versed in basic knowledge of MMF2.
And to show that I have indeed read the rules, here you go: four screenshots.