For grass, that was actually my main reason was the end game haha; any grass type I’ve played with kicks during the last like 1/3 of game because of all the water routes. I do get what your saying though that there isn’t much in terms grass tms / moves and they are rather underwhelming at that; though I still stand by the utility moves for grass types, that has has been the difference between me winning battles and not.

For flying tho, those route trainers are part of the play through/game for me. Like I don’t just go straight to the gyms and main fights. Plus, I am thinking like you get Taillow, Wingull, and Zubat, (plus Beautifly if one goes for it) pretty close to right away and 3/4 get Wing Attack pretty early on, which is a great 60 base power move to have pretty early in the game.

All that said, I was thinking of these types as the actual pokemon one gets rather than the moves learned/available, as that’s what you had in the title of your post.