What stick flex do the pros use?

Answer 1

This is like asking what size skates do the pro's use. The answer is it varies. Flex is a personal preference. Some players, Like Chara, use sticks with flexes of around 130, some players use flexes as low as 80. It all comes down to your physical size and preference.

but here's some general rules:

A small built player or younger players often use a lower flex stick.

Taller and/or physically stronger players often use a higher flex.

Try a few different flexes out, see which suits you. The worst thing you can do is pick a flex purely because a favorite player uses it. This will not help your game at ALL, It'll more likely have a negative effect.

Hope that helps