You can get a Chansey around Fusica City close to the bridges. If you want an Aerodactyl, you can trade a chansey with a lady in the grassy area that you have to use cut to get into.
Chat with our AI personalities
Give it a soothe bell and grow it a couple lvls
Level up a Happiny in daytime while it's holding the Oval Stone and it evolves into Chansey.
Happiny evolves into Chansey. It evolves with a oval stone in the day
One needs to increase Chansey's happiness to its maximum.
Chansey > level up with max happiness > Blissey