In the working dog world there are tests that are pretty accurate in determining which puppies have what it takes to enter the working dog world. Bulldogs can be tested just the same for some of those same characteristics. Just one example is that with the entire litter of puppies is in a room and not paying attention to you, just being puppies, throw a set of keys on the floor amongst them. The positive sign is for the pup to notice the keys and then go to investigate. The negative would be to cower down and run away from the noise. This same test would be used to identify the outgoing confident pup vs. the shy one.
For me, it has two kickers. Kicker one is that their raising and their enviroment can trump either puppy test conclusion just the same with the working dog. The next kicker is 'game' can come from any dog with any characteristic. The shy dog can avoid people but get it done in the box. And the opposite is true as well, the aggressive puppy may find out this is not the life he thought it would be. And every combination in between is possible.

My best example would be in the show world. Puppies can be deemed show quality vs. pet quality at 8 -10 weeks old. A smaller percentage of pet quality dog will mature into show quality dogs, but odds are they are neutered for their pre-determination as a puppy, so improving upon this dog is an imposibillity. A larger percentage of the dogs deemed show quality fall apart as yearlings and someone has spent $$$$ for a non show animal.

But yes, traits/characteristics as an eight week old puppy can be used as a direct link to what you will have as an 2 or three year old, both good and bad. The truest test is time. So these puppy characteristics/traits are not the end all/be all of choosing puppies. After that babbling, there is a correlation between puppy hood and adulthood, it is not an absolute, and once the correlation is established, the game factor can be like the trump card either way. EWO