>>57270400First of all, you likely don't mean intelligence. Likely the kinds of words you're looking for is stuff like sentience and sapience which relate to cognition. How "alive" a creature is a different matter to their intelligence. Anyway. All species of Pokémon in the main games and main anime have at minimum human-level cognition with some exceeding humans. All Pokémon can understand what humans say and other Pokémon. The Pokémon are just speaking a shared language that humans don't understand.
N can understand what Pokémon say, he directly talks to the player's Pokémon and can translate what Pokémon say.
There's also Dr. Footstep who translates what the Player's Pokémon says.
https://bulbapedia.bulbagarden.net/wiki/Dr._Footstep/QuotesTeam Rocket's Meowth learned to talk in a human manner just with practice. Most other Pokémon could talk in a human manner too if their biology allows for it and they feel it's worth learning which most don't feel the need or they have some other means like telepathy.
https://bulbapedia.bulbagarden.net/wiki/Talking_Pok%C3%A9mon 