get a pokemon about level 60, or you can get a level 100, give your weak pokemon a exp.
share, put him on the front of your team, if your using a level 60 be sure not to have to
much money, go fight the elite four with your weak pokemon up front and then change to the
strong one kill the pokemon and the weak one gets most of the exp. and then when it asks
you if you want to change hit yes and put your weak pokemon up again, reapet

wild chancey rarely hold a lucky egg, that item increases exp. gain

ok go to the pokemon center (any) and then talk to chansey and she will give you an egg

Fly to Solaceon Town and go to the man standing in front of the day care centre and talk
to him. Then go inside and talk to the lady at hte counter. Give her the pokemon you want
to level up and exit. If you go back in, you'll see a man at the table. Talk to him and
he'll give you something. (I forgot what the Poke app was called)
Every step you take when your pokemon is in the day care centre, your pokemon's exp will
go up by one point. If you put a pokemon in the day care when you first get up to Solaceon
Town, defeat the elite four when you get up to it and when you return, your pokemon should
be leveled up! But you have to pay to get your pokemon out. You can also put 2 pokemon in
their. If you put a Male and Female pokemon that are the same, you can make a baby
pokemon. (Eg. Male and Female Chansey.)
There are also mixed eggs like Ditto and Manaphy to make Phonie!

Hope it helped!