All those question marks mean is that the pet's talents has not been unlocked yet. When you receive a pet, whether through hatching or drops, it has a list of talents it can learn. When you decide to train your pet, for each time it levels up, more of those question marks are filled in with the talents that are unlocked with the leveling. At Baby, the pet will have no talents, at Teen, it will have one, at Adult, it will have two, and so on and so forth. If you feel like you have a good pet with good talents, then train it and make sure to feed it snacks, since it helps give more points for your pet to level up quicker.
