In pokemon platinum it said that i can find it in Eterna City so i thought it would be an egg but i went through every single building and i can't find it and i need it to battle gardenia i have a Grottle !!! and this is really an SOL situation can someone help me please and please don't tell me it's after the gym battle
After the gym battle Cynthia( the elite 4 champ) will give you the egg if you have a free space in your party
Cynthia gives you the egg when you have beet the gym and team galactic
Once beeten team galactic she should walk into you and give you the egg before you go to the bike shop
You will need a space in your party
For more info Here
Once you have beat the second gym leader, Gardenia, Cynthia will give you a Togepi egg if you have space in you party.