Pokemon are usually instinctive or reactive like an average animal. You have a hand full of exceptions like Alakazam which based on it's pokedex from multiple video games (Red/Blue, Silver, Sword) all make quote of how intelligent they are. Having an IQ of about 5,000. For the record the average human IQ is within range of 85-115.
I'm wondering how it would work if Ditto took form of that, but needed to switch into another pokemon to counter Ben's other aliens. Would it still operate with an IQ of around 5k or would it just go back to countering Ben's aliens instinctively?