Got my completion percentage to 88, but it is surely to go down as I just started FFX. Though, I need to hear it from you, is that bad? I do want to finish my other games, but I am getting burnt out. Would you advice going back and forth between games?
The treasures from Adventure mode as well as the competitive came very quickly for me. The rest, which are found in Arena/Hunter Arena, also dropped very fast in the beginning, then phasing out more slowly in the end where as I turned to mainly SS (splitscreen) boosting, with some legit matches in between.
Perhaps I've spent 150-200 hours in total with perhaps half of those boosting for treasures only. With the assistance of ruler2009 and a dedicated team, that time would be cut considerably. So with the right preparation, you have nothing to worry about.
It's understandable that you don't exactly jump over it Krid. As I told Racer - contact ruler2009 or ruler 2010 - they're diehard veterans who do nothing but beat the various co-op modes on crushing (look for them on Youtube).
The other important bit is to find descent booster partners, as well as 2 turbo controllers if you want to spare your thumbs (and the x buttons). Then proceed to boost all "Assassin", "Head Hunter" and "Here, You Dropped This" medals.
With the cash earned from the co-op, you invest them in weapon, booster and kickback upgrades for the competitive modes. Use mainly cloaked and perhaps monkey boy, as those 2 boosters will keep you stealthy and highly mobile. Try and collect any favors you can from people. Any help in competitive - especially 3TDM - will be worth its weight in gold as that mode is hard to boost and the opposition can be extremely fierce.