I can’t see Litten having a rock subtype personally. It’s a good theory, but at the same time typings tend to usually match up with a Pokemon’s appearance.

I don’t wanna be the one to say it… but if Litten becomes a fighting type and Popplio becomes an ice type, it works in a triangle too…

I keep seeing theories like this.

People keep trying to make up mundane rules and patterns on how things in the series work. I sincerely hope Game Freak doesn’t let their creativity be hampered by such things. I’m thinking the whole type-triangle of XY was just a thing that happened to work well with the theme they were going for.

But, it wouldn’t be the first time our predictions were correct based on pattern. I mean, remember when we got Pokémon Z? That was great! Pokémon Gray was pretty fantastic too. Also remember when Xerneas turned out to be Light type and Yveltal was Sound type? Good times.

I’d love to see the starters just drop the primary type by the 3rd evolution. Can’t think of what the other two would be, but I could see Litten becoming a Poison/Rock type.

While that sounds interesting, I don’t think there’s ever been a case where a Pokémons primary type changes during evolution. Correct me if I’m wrong, but I can recall cases where the secondary type changed, was gained or even dropped, but nothing for the primary type.

I was talking about mundane rules earlier, but if there’s one thing that seems to be a constant, it’d probably be this. I’d love to be wrong on this one, but I wouldn’t be surprised if this was something noted down in the creators bible.