This achievement is for getting a squad rating of 85 or higher and then entering and playing a match in any tournament.
Basically you're going to need mid-high 80s rated players to earn an 85 rated squad. Subs count but reserves don't. Having said that make sure you put your highest rated players in the first 11. (You can have multiple goalkeepers in the frst 11, doesn't matter where you put them).
To get a squad rating of 85 you will need all of your players ratings to add up to at least 1521. The example squad below adds up to 1521. Having looked around the market, i think this is the cheapest squad to assemble. I have also included a rough price guide of how much each player usually goes for. It will definately earn you the achievement because its the exact squad used for mine.
Good luck :)
EDIT: Updated prices
CF: 85 Rossi (Villarreal) – 4k
ST: 86 Gomez (Bayern Munchen) – 9k
RW: 85 Reyes (Atletico Madrid) – 5k
CM: 85 Sahin (Real Madrid) – 6k
CDM: 85 Cambiasso (Inter) – 5k
CAM: 84 Danny (Zenit) – 1k
CB: 85 Nesta (Milan) – 4k
CB: 85 Samuel (Inter) – 7k
CAM: 84 Hernanes (Lazio) – 1k
RM: 84 Farfan (Schalke 04) – 1k
GK: 85 Steklenburg (Roma) – 4k
SUB: 84 Akinfeev (GK – CSKA Moscow) – 1k
SUB: 84 Diego Lopez (GK – Villarreal) – 1k
SUB: 84 Adler (GK – Bay. Leverkusen) – 1k
SUB: 84 Gotze (CAM – Bor. Dortmund) – 1k
SUB: 84 Santi Cazorla (RM – Malaga) – 1k
SUB: 84 Joao Moutinho (CM – FC Porto) – 1k
SUB: 84 Hamsik (CAM – Napoli) – 1k