They have to be big enough to carry you, but even the ones that start out small can grow, and they have to be able to learn the move Fly.
Gyms are places that test your strength and make sure you're worthy or something. You can get Fly from defeating an elite trainer in a place called Cianwood City, and Surf from Olivine City, but you have to defeat two other gym leaders in order to use them if you're a trainer. You can just borrow the moves from someone else, if you're a breeder. Which one are you?
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Gyms are places that test your strength and make sure you're worthy or something. You can get Fly from defeating an elite trainer in a place called Cianwood City, and Surf from Olivine City, but you have to defeat two other gym leaders in order to use them if you're a trainer. You can just borrow the moves from someone else, if you're a breeder. Which one are you?