FIFA 21

Easy but potentially a very lengthy and grindy achievement to get that requires you to complete 120 games in any FUT mode. In order to unlock the Tier 3 Stadium you have to complete the first tiers of Stadium Development in Ultimate Team Mode.

Go to Ultimate Team / Objectives / Milestones to find the Stadium Development objectives. Tier 1 you need to complete a total of 50 matches in ANY Ultimate Team game mode to unlock Tier 2, where you must complete an additional 70 matches to unlock Tier 3 and the achievement.

Game modes that count:
Squad Battles - you vs the AI team. You can play on Beginner difficulty and make this very easy, albeit time consuming as each match is at least twelve minutes

Division Rivals - you vs other players in online matchmaking. More time consuming than Squad Battles because matchmaking is slowing down with the newer games out so it takes awhile to find a match let alone 120

Friendlies - either you vs AI or online players in special match types. This mode has a huge negative as games played here do NOT count towards the 200 games with a player achievement, HOWEVER the Online Friendlies can be boosted and thus save you a lot time.

Meaning you can match up with a boosting partner or dummy, have them score three quick own goals to end the minute in about a minute. This means you can do the achievement in a matter of hours rather than the 30+ it would take to get the achievement playing full games.

Unfortunately there is a catch to this: FUT online matchmaking won't let you play the same account consecutively, you have to play others before you can play the same one again. Using four accounts I created a system that worked perfect for me:

Account 1 = A1 (account getting the achievement)
Account 2 = A2
Account 3 = A3
Account 4 = A4

A1 v A2, A1 wins
A3 v A2, A3 wins
A1 v A4, A1 wins
A3 v A4, A4 wins
A2 v A4, A2 wins
A1 v A3, A1 wins

At this point you've cycled through everyone and can repeat the ladder again. This is a very boring and tedious process, especially if you're doing it with another person or only have two Xboxes but saves SO much time in the long run.

Notes:

• After you complete each Tier, make sure to claim all the prizes in order to unlock the next tier
• Like FIFA 20, the FIFA servers can't seem to handle excessive forfeits. At some point you might start getting disconnected from the EA servers after every game ends, not giving you credit for a complete game. If this happens you'll unfortunately have to wait a day or so for the servers to catch up and resume
• You'll unlock the FIFA Ultimate Theme achievement on the way to 120 games. It should unlock early into Tier 2 once you've unlocked 20 different items for your stadium
• You'll also unlock the Seasoned to Perfection achievement for completing two milestone groups if you haven't gotten that achievement yet
• If you're going for both stacks of the game, this achievement will autopop on the other version shortly after logging into Ultimate Team