After that you continue your trek up Route 1 with Bulbasaur.
(now here's where it gets exciting)
You enter Viridian City, and you immediately notice something wrong: there's guys in black suits with red Rs on them all over the city! This could be bad, but if you need to take action you shouldn't just charge into danger...right? So, what do you do? They're everywhere, and they seem to be blocking the PokeCenter the most...which is a problem for Bulbasaur. It could be a dangerous situation. Maybe you should flee for a while.
Choices 1) Ask the Rocket blocking the Pokemon Center door what he's doing
2) Ask a different one what they're doing here
3) Start a fight with one
4) Flee and go to Route 2
5) Flee and go to Route 22
(for now on, the choices you make WILL affect the plot.)
>Flee and go to Route 22 "This is dangerous," you think. So you sneakily leave Viridian and leave to Route 22.
You feel bad about just leaving Viridian like that. People are probably getting hurt and you didn't do a thing to help. But wait, maybe you can help! There's a building in the distance that looks pretty important. Maybe there's people that can help you! You could also perhaps try to catch some Pokemon, then you can storm Viridian. It's your choice.
Choices 1) Look for Pokemon
2) Go to the important looking building in the distance
3) Go back to Viridian