I haven't been able to find a script like this, but if there is one like it out there, please let me know.
I would like to know if there is a script that upon a command, will switch the main actor to a secondary main actor. Who has a completely different party.

Is this possible or do I have to make two different games with their different views? o.O

Is this what you're looking for?
http://rmvxp.com/showthread.php?tid=338

Not exactly but close. Thankyou anyway.

This magical script needs to make it so you can switch the main actor to another main actor, who has a completely different party from yours >.<; blegh.

You can do it with events on the map you just add/remove all of the characters till you get the configuration you want (not on my computer otherwise i would show a picture) And if the party's are on different maps what you do is use teleport to Town/place and then you can give it the effect of a script :)

Take a look at this section http://rmvxp.com/thread-781-post-2197.html#pid2197 of the forum script listings, there are a few scripts that may be of help.

Do you mean like this for example:

Hi, I am Darwin in the mountains on an adventure!
*Switch*
OMG! I am Gramps about to get eaten by a monster!

1. Like you have two parties on two different adventures in two different places, and you switch between them occasionally?
2. Or do you want it so you can switch when THE PLAYER wants to?

The first one you can do with events. The second one might need a simple script.