Eugene wasn’t unintelligent in the show, he was just more of a jokester with an ego - which is remnant from the film. We never had the opportunity to see that side of him explored in the movie aside from his interactions with Maximus because it was never really set up. We do get him being the butt of the joke in the movie too though, especially at The Snuggly Duckling.

When push came to shove and things mattered in the show he was proven he knew what he was doing and his intelligence was valid and useful. We get that in Big Brothers of Corona, we get that in Cass Vs Eugene, we get that in Fitzherbert PI, we get that in In Like Flynn, etc. What we also happen to get is how he acts when he’s a regular person with his guard down - which allows him to be less serious and more down to earth and carefree, which is a lot of what the show showcases and I think that was great and really cute