I know I can't add friends since I made the profile for my 6yo, but can I still battle another trainer in the Great League? If not, why are they giving us special research tasks we can't complete? Lol. Thanks everyone!
Yes, child profiles are able to do PvP Battle Leagues. If your child's profile is currently unable to use these feature, then you can enable it accordingly through the various portal sites
If your child logs into Pokémon GO using Niantic Kids or Pokémon Trainer Club (PTC), you can opt into enabling social features such as Friends, Gifting, and Trading and Trainer Battles for your child in either the Niantic Kids Parent Portal or Pokémon Trainer Club website. You can also revoke your child’s access to these features at any time.