After finishi all the stages of the quest, I went to talk to the baby lugia to finally capture it, but the NPC shows me the dialog box: 

"it looks like you dont have enough space to catch any new pokemon anymore", I went to the PC and deleted some pokemons, restarted the PRO, but the same message persisted in appearing.

Please, I would like to ask for help so I can complete my mission and receive my reward.

The icon on the top-left tells you how many more pokemon you can catch and it is at 0 right now. You need to release more pokemon to catch new ones.

Even after deleting 30 Pokémon, and making a new capture of a Magikarp, showing that there is exist free space, the message keeps repeating "it seems that you no longer have enough space to capture any new Pokémon"

23 minutes ago, Norex said:

The icon on the top-left tells you how many more pokemon you can catch and it is at 0 right now. You need to release more pokemon to catch new ones.

Even after deleting 30 Pokémon, and making a new capture of a Magikarp, showing that there is exist free space, the message keeps repeating "it seems that you no longer have enough space to capture any new Pokémon"