Thank you for your question.
Am i right that those 3 are all same kind of plugins?
No, they are same.
Drag and drop page builders?
The Unyson is a required plugin but its page builder is optional which is grag and drop builder.
The WPBakery page builder is a drag and drop page builder.
The YellowPencil is a WordPress CSS style editor plugin.
Do i need them all?
No, the only theme required plugin is a Unyson plugin and all other are optional.
Thanks for your reply.
But when i deactive wpbakery and yellowpencil plugins, i got these messages :
The following required plugin is currently inactive: WPBakery Page Builder.
The following recommended plugin is currently inactive: Yellow Pencil Pro.
Why do i got this message, while you say they dont needed? Thanks again.
The Yellow Pencil Pro is a recommended plugin and not a required plugin.
The WPBakery Page Builder is a required plugin If you are using its functionality.
You can just dismiss that notice by clicking on the “Dismiss this notice” link displayed below the notice.