first try to get carriers with fighters then you can lagh at his scouts, and if you have the econ build a SB at his HW or yours depending on how badly he is beating your fleet. Scouts will not be able to take down a building SB unless he has hundreds of htem because they do poor dmg to SBs. if you scout ahead and see him getting alot of scouts tech up to carrirers as quickly as you can.

In case of Marza, you probably want egg to chase the marza away, which an egg will happily do.  Egg has nothing to fear from the scouts, and u get a fighter squad whereas the Marza has none.  If he is rushing you he probably took Raza planet, Marza might beat egg if it has radiation bomb thou, so watch it.

The last game where I fought this particular battle both caps died, egg before marza, if one was to survive it was going to be the marza most probably, even though he had raze planet.  The reason for this is not because the Marza is better heads up, it's isn't as nanos > all.  But, the scouts are indeed dangerous to the egg.  As the first thing the scouts do is go thru and kill off all the constructors, so repair bays if you have them at all are rare and not necessarily where you need them to attack the marza.   Then it's just volume of fire on the egg.  A swarm of scouts will kill it eventually and there's no real escape until you can get sufficient fighters built to swat the scouts (which takes a surprisingly long time), however when you do the scales will tip rather quickly and dramatically and thus I was able to task my strike craft with killing the marza before it could escape.

Yes, this is a bad situation for Vasari, but you should see it coming when you see the other guy massing scouts and moving his Marza towards you.  Vasari should always have built at least one military lab, so try and get a repair structure up and a turret or two.  Use a combination of LF's and your own scouts to fight him off, using your Egg against the Marza.  The key is having a repair bay up.  Flak is good too, if you had time to get it.  A good rusher will be on top of you before you have carriers...but if they are dawdling, you can try and get them if you have time.

Top Vasari I have to disagree, while his scouts won't be able to stop a starbase from going up he can eat up any assailant force you try to mass, and he will be able to kill the starbase before it does too much damage, meanwhile the mazda is free to eat your homeworld.   It's not gonna work that way I'm sure of that much

We're talking about a rush.  As in, you just finished colonizing your asteroid with your Egg and all of the sudden a Marza and 20 scouts show up.  Assuming you WERE going to attack first with a handful of Assailants, they will lose to the scouts.  A SB will be effective if you get it up quickly, but you can't afford both Assailants and a SB this early, without heavy feed. 

Assailant rushes don't work against people who build scout armies.