Potentially millions of others have been given morphing abilities, but most known examples didn't retain the ability. Here there be spoilers.
Two animals also managed to obtain morphing ability in Book 39, The Hidden. Aka, an African cape buffalo, and the fire ant nicknamed Cassie-Ant both managed to obtain morphing and human forms in one escapade. Cassie-Ant was squished shortly after attempting (and failing) to assume human form, and Aka was shot by a Controller.
David wasn't an Animorph when he obtained morphing ability in Book 20, The Discovery, and was either dead or stuck as a rat at the end of Book 48, The Return -- his fate isn't revealed.
Furthermore, Yeerks in the Yeerk Peace Movement may have (as the most well-known leader, Aftran 942, was in Book 29, The Sickness) been given the option to assume new permanent forms, but their fate isn't discussed after losing communication during the war.
At the end of the war (Book 54, The Beginning), all surviving Taxxons were given the choice to morph into snakes so they could finally be free of their racial hunger. This was also extended to Yeerks who wished to be free of their reliance on Kandrona and hosts.
It is then, in time of supposed peace following the war, that we see the one non-Animorph group to retain its morphing ability: Jake agrees to train special forces in the art of morphing. From these, he chooses Santorelli and Jeanne Gerard to create the New Animorphs group, with the purpose of finding Aximili, who had been separated from his group in deep space while on a mission to find the Blade Ship.
As we don't know about events outside the scope of the books, it's impossible to say if there were not other races given morphing ability by the Andalites -- the books are inconsistent in regards to the age of the technology; it's both regarded as new and yet it's also said that Andalites have already spent their lives mastering a few forms for the sake of subterfuge. The technology, if new, may not have had time to spread to allied (and enemy) groups yet.