There are a few ways to do this.
But BOTH ways I'll tell you will still require the Adrestia to have an improved Hull, you must upgrade the Hull to the legendary status.
1) Buy Evie Frye from the club and buy all the legendary leiutenants from the store via Helix credits.
2) Invade forts of the different continents. Once inside, use Ikaros to find out their stats and recruit them by knocking them out and then recruiting them.
Once you have four you can unlocl the trophy.