The servers have now closed, thus the Platinum is unobtainable.
-Estimated trophy difficulty: 5/10 Platinum Difficulty Rating - PlaystationTrophies.org
-Offline: 36 (26, 6, 3)
-Online: 11 (10, 1) - Unobtainable, due to server closure.
-Approximate amount of time to : 8 to 10 hours
-Minimum number of playthroughs needed: 2 or 3
-Number of missable trophies: none (chapter select)
-Glitched trophies: none
-Do cheat codes disable trophies? Yes
First off, note that the Japanese version is the only version with a trophy patch. So if you want the trophies, you will have to import it from Japan. This game has gotten some pretty bad reviews, but I like it. It's very similar to Saints Row 2 (which I love). Maybe because it stars this wack ass rapper ! (just my opinion)
Step 1: Online - Easy Co-Op Playthrough - Unobtainable, due to server closure.
Start off by finding a partner in the boosting thread here: CO-OP Partners (Read First Post!) - PlaystationTrophies.org.
Make sure you and your partner both have the Japanese version of the game. Then run through the game very quickly on "Easy" mode. This way you'll open all the stages on Chapter Select (you'll need this before you start your "Hard" run). More on that below.
Complete two playthroughs of the game. One as 50 Cent and the other as a member of the G-unit. This way you and your partner will earn all 12 online trophies. Also, don't forget to die on purpose to get "Not Bulletproof" and revive your partner to get "Savior".
Step 2: Chapter Select/Weapon Trophies
Alright, here is a cool trick I saw on our sister site. Since you already beat the game online, you'll have all stages available in Chapter Select. Replay the last chapter of mission 8.
In the general area of where you start, there's around 80,000 dollars. Collect all the money, then push and choose "Replay Last Checkpoint." You'll restart, but you keep your money every time. Keep replaying this checkpoint until you have 1 million dollars and you'll get "Millionaire". It should only take around 20 minutes to do.
Now walk over to the phone to purchase items. Buy every gun and you'll earn all 5 weapon trophies including "Tooled Up". Now buy every counter to get "Black Belt".
best thing about this trick is when you start your "Hard" run-through, you'll have every gun, making "Hard" mode A LOT easier!
Step 3: Story Mode - Hard Offline Playthrough
Make sure you start on "Hard" mode. The difficulty trophies are stackable so you'll get the trophies for "Easy" and "Normal" mode as well. "Hard" mode is not very difficult. Just use cover if you need it because you will die pretty quick. Also only use "Gangsta" mode when you need it.
Try to get a gold badge on each stage during this playthrough. You get gold badges by scoring a certain amount of points. Push to see the score you need for the gold badge for each stage.
[In each stage collect every poster and shoot every target for major points. Also, always try to kill 5 guys in a row to get "Massacre," which earns a lot points as well. Here is a link to some video that will help with the gold badges (Video Achievement Guide - Posters,Targets,Gold on Hard! - Xbox360Achievements.org).