Tiger Woods PGA TOUR 13

You first must have the "Toddler Years" achievement unlocked for completing the first section of the Tiger Legacy challenge. Get a group of 4 together with the same achievement to begin. From there you want to create a PRIVATE session so no randoms join in. Scroll over to the Xbox Live tab and click lobby. From here scroll to game mode and click stroke play (I find this to be the most reliable). Press Y to create a game session. Here are the settings I used.
Unranked
Yes for private session
Max players 4
You can leave everything else as is but make sure you use a course everyone has like TPC at Sawgrass. Once you create the session scroll left and you should find Toddler Tiger. Select him and it will say you are playing as Tiger Woods. Send out the invite to your group of 4 and have them select Toddler Tiger. Once everyone has selected him have everyone press A to ready up. The game should begin and everyone should unlock the achievement in the loading screen.

If for any reason you are having some people kicked out never fear as EA servers are notoriously shitty during a games launch and sometimes even later. Cycle host to see if someone has better luck. With my group the first 2 hosts were unable to keep everyone in the lobby for more than 5 seconds until I set up a game.

Short and sweet;

First unlock the 'Toddler Years' achievement by completing the first part of Tiger Legacy challenge.

Create or join a boosting session to get 4 people, all add eachother as friends.

Go to Xbox Live - Choose stroke play.

Press Y to create a game session and choose the following settings;
Unranked
Private Session/Friends Only
Max Players: 4
Course: TPC Sawgrass (needed because many others are DLC)

None of the other settings matter, the achievement pops when everyone clicks start (Ready Up)

Invite the 3 other people.

All choose Toddler Tiger (click left from full size Tiger)

Press A to ready UP.

The achievement is yours, easy 15G.

If some people get disconnected, try again but someone else set up the game.

I have been told it is possible with 2 controllers, by a friend who has the cheevo. I myself did it by making a boosting session and finding 3 people.

I also did it using the 2 day online free pass.