You can just go into Wolfpack and kill the targets quickly. I am up to Rank 14 and I started earlier today. I'll hit Rank 20 later tonight with no problem. You can even do that method by yourself if you don't have anyone around. You can also do the hack Video and reach Sequence 10 while doing this. All very easy.
100% Completed: 226 | Total Games Played: 229
Current Percentage: 99.78%
Currently Working On:
Rayman 3: HD
On The Back Burner:
Ninja Gaiden II & Trials: Evolution