Saints Row 2

For the achievement to work for both players, each activity listed below MUST be completed in co-op the first time you playthrough it on a new game file.

-Crowd Control
-Demolition Derby
-Drug Trafficking
-Escort
-Fight Club
-Fuzz
-Heli Assault
-Insurance Fraud
-Mayhem
-Septic Avenger
-Snatch
-Trail Blazing

This is very very important. If you complete even one level of one activity solo before doing so in co-op, you need to make a completely new game.

The bug with this achievement (and the stats that go along with it) is that the game only recognizes the first time you play an activity, not replays. So the reason that some people are not getting the achievement while their co-op partner did is because they played something solo before they did co-op.

So my advice is for each player to make a new game and only play activities together. That way you are both on the same page about what activities have been completed.

*** This is a solution only if you have encountered the problem that myself and my boosting partner did and I am posting it so that should anyone find them selves in the same situation they can solve the problem without the need to suffer every single activity twice***

When we got to the end of our activities list which totaled nearly 14 hours we found that I had gained the 23/23 required and got the achievement and my friend had only 22/23.

After scratching his head for a couple of minutes and thinking long and hard about what he had done it dawned on him that what he had neglected to do was start a brand new save file and had already started 3 rounds of FUZZ on that particular character.
Faced with the prospect that we may have to encounter doing all of them again we struck up this plan. As you may know once you have even entered a activity on that save it can not be counted in co-op.

We both created another brand new pairs of save files, When looking at the stats in these new game saves the co-op stats page read the same as the our first completed saves 23/23 for mine and 22/23 for his. We did the first mission to get the ball rolling and then went straight for the activity that he had previously started. Upon completion of this activity it counted as the 23 and he got his achievement.

Now we knew which one that was going to be the issue, and if you have been foolish enough to create a similar headache for yourselves, I just hope that you can remember also.

I hope that this comes in useful for someone, and that It doesn't just receive a sting of negative votes. If you have any questions about my solution then feel free to send me a message on TA and I will get back to you as soon as I can.

Okay, Phil the guy has already written a very good guide (it got my thumbs up), but while following that guide, I was surprised by the co-op variation of some activities, so I'm writing a guide about the differences between the solo and co-op, just to make strategy easier (Phil if you want to incorporate it in yours, I'll gladly delete mine).

Crowd Control- Can actually get pretty hectic in the later levels, with as many as 5 or 6 stalkers after your celeb, stay on your toes.

Demo Derby- Be quick in later levels or they'll destroy each other before you get the necessary damage in.

Drug Trafficking- No change, easy as pie with a homie to revive you.

Escort- Remember the Ho'ing Diversion? Whoever initiates this activity is in the backseat, pleasuring the client, the partner is driving and avoiding news vans.

Fight Club- The same, only a significant increase in opponents (think it was 8 at level 6).

Fuzz- No change.

Heli Assault- Initiating player is the pilot, partner is on weapons, much easier in co-op.

Insurance Fraud- Higher totals needed, ignore adrenaline zones in favor of interstates (and the lovely fast, non stop big trucks they bring).

Mayhem- Again higher totals needed, fences and Al fresco cafes make this ridiculously simple (my partner and I's highest combo was 214).

Septic Avenger- Initiating player is the only one who can brake the septic truck.

Snatch- You can only pick up one girl at a time each, but you can use separate cars, and go separate places for pickup, insanely easy with a little communication.