Join Nix across the hell that is Kanto and all its Pokemon, specifically the poison types. oh god, the poison types...
Mostly Basic rules:
1)Pokemon faints, it dies.
2)Can only catch the first pokemon on a route
-If it's a duplicate you may retry
-Exceptions include shinies and gift pokemon
-No catching Legendaries
-Each area in the safari zone counts individually
To be fair, Hyde carries everything. So Green just probably forgot he picked one up.
Him and Falkner got their birds in viridian forest; pidgey can evolve real young there.
Except if you're a protagonist to something, then you'll always catch the one normal pidgey. It's poke-law.
Grind a lot early on, that way it's not as hard later on when all the wild pokemon are really low leveled...