In the cartoon Smurfs, Gargamel had a solid brown/orange cat named Azrael. In Smurfs The Movie, which has computer animation for the Smurfs, and live actors for the other characters, Hank Azaria plays Gargamel, and a striped orange cat plays Azrael. (It is the first CGI/live-action hybrid film produced by Sony Pictures Animation and in The Smurfs trilogy.)
In Smurfs 2, it appears a CGI cat plays Azrael. In this account of the special effects used for the movie, it is said that four orange cats were used in the movie for the part of Azrael, but that a composite version was created in CGI for sequences in which the cat had to emote, or to do something dangerous.

Article about NYC locations used in the movie, from the NY Daily News;
‘Smurfs’ and the City: The beloved creatures painted New York City blue for their new movie
BY Gina Salamone
Sunday, July 24th 2011, 4:00 AM
From SoHo to Central Park, New York City has been invaded by little blue creatures.
“The Smurfs,” arriving in theaters Friday, is a movie set against the backdrop of the boroughs – thanks to a blend of live action and computer-generated imagery.
The brand began as a comic strip series by Belgian cartoonist Peyo in 1958. But most Americans know them from the hit animated TV show that aired on NBC from 1981 to 1989.

“From our point of view, the way to translate the cartoon in a different and interesting manner that takes the Smurfs out of animation and into live action, was to put them in a world that would highlight that change and the distinctions from their village,” says the film’s producer, Jordan Kerner.

“We start in their village, so we get to see and love it,” he says. “Then we get to see them in another world and test them against it. And of course, one of the most interesting and complex environments they could ever enter would be Manhattan.”

In the cartoon, the tiny blue-skinned beings lived in mushroom-shaped homes in a forest. The film begins in the Middle Ages with the Smurfs being chased by evil wizard Gargamel (played by Hank Azaria). They flee into a portal that plants them in present-day Central Park.

“They’re of course amazed at what they call our village,” Kerner says. “And it’s something they’ve never ever seen before, coming from the 14th, 15th century in Belgium. They’ve seen little human villages but nothing on the scale of this.

“New York City provided very interesting, colorful and physical backdrops for the little blue things,” he says. “It enabled us to put them into an environment that for them might seem hostile, where there’s a lot of people walking and moving. Like going onto a subway could be a very dangerous thing for them.”

While some scenes were filmed on sets at Kaufman Astoria Studios in Queens, many others were shot on city streets.

“We’re thrilled that ‘The Smurfs’ filmed at some of New York City’s most iconic locations, taking advantage of our great locations and talented crews,” says Katherine Oliver, commissioner of the Mayor’s Office of Media and Entertainment.

The Smurfs did just about everything – from taking a taxi through Times Square to skateboarding through FAO Schwarz.

“Having Gargamel walk around Bryant Park, with extras and with civilians, very few people commented or found him odd ,” Kerner says. “It’s New York City. You’re used to seeing everything. So we had people who were in the movie, who would turn around and look at him, like, ‘Whatever.’

‘Only once did Hank get a comment from somebody w ho recognized him from the cartoon,” he says. “It was something along the lines of, ‘Hey Gargamel, you’re really cool.’ Other than that, he was treated as another guy walking down the street.”

This worked well for the filmmakers, who had a lot of ground to cover in just seven months.

“We were very happy that the studio was generous enough, and that New York has incentives that allowed us to shoot there, rather than shooting in Toronto, and going to New York for one week, which is what a lot of films have done and continue to do,” says Kerner.