Alexa may have stolen the show at the Consumer Electronics Show (CES) earlier this year, but it's Assistant that is in the limelight now. At the Mobile World Congress, one of the biggest industry conferences in the world, device makers launched a number of smartphones that come with Google Assistant already installed. Google Assistant is the search giant's artificial intelligence-powered voice assistant to rival Siri, Amazon's Alexa, and Cortana. It was introduced last year to replace Google Now, and was originally only available on the company's Pixel smartphones, its smart home speaker called Google Home, and via its chat app Allo. But on Monday, Google said it is beginning to roll out Assistant to all phones running its Android operating system version 6.0 or newer. Google Assistant was introduced on LG's new G6 smartphone and the HMD Global Nokia devices at MWC.

The U.S. technology giant's move comes after Amazon continues to aggressively push Alexa onto new devices. At CES, Amazon announced Alexa would be integrated with LG refrigerators and even Ford cars. But it began to step on Google's feet when Amazon announced that Alexa would be on the Huawei Mate 9 smartphone in the U.S., which runs Android. "It is little surprise Google has come out with all guns blazing at MWC. It must be reeling from the decision to include Amazon's Alexa on the Mate 9 when it was announced," Ben Wood, chief of research at CCS Insight, told CNBC by email on Tuesday. "Amazon has taken an early lead with Alexa and Google needs to exploit the enormous reach of Android smartphones to rapidly get the Google Assistant into the hands of consumers before they get wedded to the Alexa ecosystem." Nearly 9 of every 10 smartphones globally run Android, giving Google a huge consumer base to start off with. "I think in general, whether this is rolling out to lots of devices or not, we now have user feedback, it will help us improve the product," Gummi Hafsteinsson, product management director at Google, told CNBC in an interview at MWC on Tuesday. "The engagement is more important to that than anything else. We get both positive and negative feedback and use that to make the product better. Hopefully, we will see the product get better faster."

Sundar Pichai, chief executive officer of Google Inc., discusses the Google Pixel virtual assistant during a Google product launch event in San Francisco, California, U.S., on Tuesday, Oct. 4 2016. Michael Short | Bloomberg | Getty Images