Are mass stalkers only a option to win games?
or which Units do you prefer?

colossi

Which Units do you build then also if the enemy got air units as well?

Storm works well vs mass air...cept like BCs or carriers lol

Phoenix?

voids or penix

excellent point....ive always wondered why pro protoss players only build stalkers

good chase unit, but ye so many units make them completely useless

all you need to kill terran is any unit that is warped in from a gateway, built at a robotics facility, built at a nexus, or built at a stargate.

Late game, Protoss players tend to build an army comprised of colossi, high templar, archeons, and zealots with a few stalkers mixed in (but only 10 or so). Against an opponent heavily committing to air, this will change and you'll see more stalkers and possibly phoenix. Some players also like to add void rays or tempest, depending on the match up.

this. you can literally 4 gate your way to masters league.