Doing a Nuzlocke

Legends Arceus is my favorite game in the series, and as such I wanted to add some replay value above "just play it again." However, the obvious catch with doing a nuzlocke is that the game operates around catching pokemon, meaning that the rule of only using the first pokemon you catch per area doesn't translate well into the game. Not only are there not enough areas, you also have full jurisdiction on which pokemon you want. How would one go about catching pokemon where it's both random and limited?

I just finished a beta of sorts, where I used a random number generator with numbers from 1-30. Whenever I rolled a 30 after catching a pokemon, I could use it. After I reached level 10 for a pokedex entry or caught 10 of the same species of pokemon, I couldn't roll the generator for any other pokemon in the family (Ex: if you caught 10 bidoofs, you couldn't roll to use a bibarell. If you finish the dex entry for a starly, you couldn't catch a staravia or staraptor)

I felt this system gave me a good number of pokemon, however I realize that if you just got lucky you could have far too many pokemon. Also, it's kind of a lot to keep track of. Any easier ideas?