The Federations Add-on for Stellaris has 10 achievements.
Be a founding member of the Galactic Community
Level up your Federation
Be the leader of a max level Federation
Build a Juggernaut
Construct a complete Mega-Shipyard
Refuse to belong to any club that would have you as a member
Have a Diplomatic Weight of over 9000
Have all eight ethics represented within your Federation
Humiliate an Empire that is in the Supremacy Diplomatic Stance, forcing them out of it
Denounce an Empire that is not actually in breach of galactic law while all major sanctions have been passed