Beat the E4 first, then talk to Celio and check again.

If that doesn't work, make sure that you caught Moltres sitting at the top of the mountain
and try again.

no you must have atleast 60 pokemon then go to professer oak then he will give you
national pokedex then when you go there you will see team rocket talking.

Where is E4?oO

u have to catch or make the fire bird faint and beat elite 4. then go to celio and then go
back to that place then they will battle u and give u part of a secret code that u need
for later.

After they're conversation, they'll notice you. Go in front of them and press A that's
where you battle with them. Hope this helps. :D