the vendors you mean the sellers or the people who hatch eggs well for vendors there is 1 and for the sellers too much : )
The pet pavilion is connected to the Commons of Wizard City.
In Wizard101, to get a pet that gives you a card in Wizard City, you need to hatch a pet that has card-giving abilities or obtain a pet from certain quests or vendors. The pets that provide cards often have abilities like "Firezilla" or "Frosty" which can be acquired through hatching or by earning them in specific activities. You can also visit the Pet Pavilion or the Crown Shop for additional options. Once you have the right pet, level it up to unlock its card-giving potential.
Wizard City, Pet Pavillion
you go to wizard city hatchery and ask someone to hatch it must be a lvl 48 pet or higher
Go to the pet pavillion in the commons,(wizard city), then play some of the mini games to get experience for your pet. If you are in wizard city and you can't find pet pavillion, click your compass on the left hand corner of your screen. It should lead you to the pet pavillion.
there is none
You have to level it up in the petpavillion
SUMMERDRADON gets you a dragon.
You have to have a pet
Nope.
When you want to train a pet, you head on over to the Pet Pavilion in Wizard City. You can get to it from the Commons. Play one of the games available, do your best , have fun and at the end of the game, if you have any, give your pet a pet snack. Repeat this multiple times. Doing so will cause your pet to gain experience, therefore training them. Eventually they will level/rank up.
You go to the Pet shops in the Wizard City and buy them for a little under 15000 crowns. :P