There is NO perfect puppy. Perfect match. Perfect companion. Or fairytale ending. This is not a Disney movie here. EVERY single puppy will be a challenge. Every puppy will encounter setbacks we cannot foresee. An example of this would be, if a puppy is taken to a dog park and they get attacked by another dog, the puppy could experience a setback. The pup could become fearful and reactive to other dogs. They have to immediately move into counter conditioning to ensure this one event does not become a lifelong fear issue.

The following is a chart that shows examples of different temperaments:

 

Assertive VS. Submissive Assertive: Your child is holding a piece of pizza. An assertive dog will walk up to the child and take it. Period.

Submissive: Your small child is holding a piece of pizza. A submissive pup will walk slowly toward the child. Look left, look right. Smell the ground. Move a little closer. Check again to see if an adult is watching and slowly, ever so slowly try to take the pizza. Sometimes they will and sometimes the child will say NO in time and the dog will respect those boundaries. 

Lacks Confidence/Nerve Strength  You cannot coddle (pet or baby talk) which enforces fear. Socialization will take longer. Let’s say you want to be able to take your pup to the park to walk around or take one of your children to the playground. You need to work the pup up to that outing; it cannot magically happen when the puppy is old enough to be in public. Day 1 may be just sitting at a bench in the park until the pup settles. Then leave. No meeting new people. No pressure. Day 2 move closer to the playground. Sit and wait it out. Fear will dissolve (they cannot stay in that state of mind for long) and then leave. No meeting new people. No pressure. Day 3 sit right next to the playground. Politely tell those wanting to pet your pup that he or she is in training and cannot visit. Wait until the pup is settled and calm. Then leave. No pressure. Respect these pups and their needs to take things slowly. Do not force. Do not enable. Build confidence through respect and understanding. 
Low Motivation Finding what this pup values is key to training. Maybe it is treats? Maybe it is physical affection? Maybe it is toys? Keep training sessions short and fun! If you want a puppy that will follow you around, willing to do whatever you say with complete obedience and admiration, this is not the puppy for you. You have to hang the moon and stars for him or her. When you take a low motivated pup home, I highly encourage you to feed by hand. This is an important part of establishing a healthy “pack” bond and leadership structure within your household. Lay the foundation that you provide everything for him or her and that you both value and respect each other. 
Low Touch Tolerance This pup, as of now, does not “love” a lot of physical affection. Generally, it will be more on their terms and more often than not, they do not like unsolicited affection from those they do not know or trust. If you have any children in your household, ensure they know that when the puppy is sleeping, they are to keep their hands off and when the pup is in his or her kennel, they cannot disturb. If you want a dog that is highly affectionate, let’s look at other options. 
Exuberant Pups It is important for these puppies to work on self-control and focus. Do not “reward the crazy,” for example, if you take the pup to the park and he or she gets excited to meet new people, do not allow anyone to pet until the puppy is calm. In fact, go often and do not allow anyone to pet him. He needs to know that excitement is not rewarded. When you get his food bowl out, if he barks and gets excited just stand there with his food bowl. As soon as he settles and sits, say “yes” (immediately) and put the food bowl down. The hand feeding, “sit on the dog” and tether training activities are very important training tools for exuberant pups. Is there a trainer lined up to help, if needed?
High Energy Are you willing to make the commitment to ensure this pup gets more mental stimulation and physical activity than most need? That might mean getting up earlier to walk longer, doing extra training sessions, challenging your pup with games and puzzles etc. It means not spending all day at work and then going to a movie or out to dinner, without taking your pup’s needs into account. Do you enjoy playing, hiking, swimming, walking, etc. with your dog(s)? Do you have help (kids, spouse, family)? The hand feeding, “sit on the dog” and tether training activities are very important training tools for high-energy pups. Is there a trainer lined up to help, if needed?
High Prey Drive  This pup gets aroused easily by sight and / or by smell. They may stay in “play drive” territory but could move into “hunt drive” and that can be difficult to manage. These pups tend to lose self-control when a rabbit is seen or maybe when kids run by or even just with toys (shaking to kill). A high-prey drive pup is not an ideal match for a family with young children or a situation in which the dog would often be exposed to young children. You will need a system in place for draining this energy appropriately (playing fetch, long hikes, etc.) and family training to the “treat” game, where no one is chasing the pup or taking items from he or she.
Low Human Focus This pup loves other dogs, or toys, or… more than anything, so if you need a dog that attaches deeply to you then let’s look at other options better suited for you both.