Something I noted while planning which Starter to pick for a Crystal playthrough where I would try to fill the dex (thus have more team options) was that If I was to pick meganium, there more or less would not be a proper grass type replacement.
This is due to most grass types having stone evolutions, and as many remember the gen 2 stone system, it would mean that its all up to rng or the very limited 2 Sun stone evolutions because of the sun stone being a prize for bug catching OR a jumpluff/parasect for a level up grass type.

Why do I bring this up? Because Meganium as a starter would be the best choice if you wish to experiment with teams and have a perma-member due to there being next to no competition for a strong grass slot.

This can to some extend be also said about Typholysion but fire types are less common in general, and the devs were dumbfucks who locked 2 new fire types to post-game, but the whole stone evolution thing seems to be a genuine issue with grass types.

As for Feraligator, the poor bastard is pitted into a sea of other water types, about double of the grass/fire amount if we count pre-evolutions.