On my current profile, I'll be maining a Beedrill, and possibly (don't like it's moves, but TMs/HMs/Tutors may change things) a Butterfree. I saw plenty of Weedils, caught the 1st one. Yet for some strange reason, that was all for a while. I don't knwo why, but it took soooooooo long to find a Caterpie! I even saw Metapods and Kakunas 1st. It took way longer than it should've.
I even stumbled upon FOUR Pikachus, while trying to avoid grass spots. I'm not interested in one, so I didn't catch any. But I think I may have sa mreo of them than Caterpie, or at least close!
Note: this was in Viridian Forest.
Anyway, I have 2 favorites, Beedrill and Parasect :D