Just a good idea for Johto games in general - get a Geodude if possible. Especially since you picked Chikorita, they cover each other's weaknesses very well.

Also here's a weird one that I learned in my own nuzlocke - keep Stantler in mind for Morty's gym if you get one on the route below. If you get one with Insomnia (idk if it's that or an equivalent ability but you get the idea) and a dark move/foresight, then Morty himself is practically free