Five Wizards got sent to Middle-earth to combat Sauron, but Gandalf is the only one seen fighting against him in The Lord of the Rings. One of these Wizards, Radagast the Brown, is briefly mentioned throughout J.R.R. Tolkien's work. And while never appearing in The Hobbit novels or The Lord of the Rings, sparse details can figure out his role and capacities as a powerful wizard.
While Gandalf the Grey and Saruman the White had prevalent roles within Middle-earth, the remaining three Wizards are shrouded in mystery. The two Blue Wizards are the most unknown, with Tolkien barely providing details about who they are and where they were during the War of the Ring. However, in Radagast's case, he has been mentioned enough to paint a somewhat clear picture of his character.
Despite being a supporting character in Peter Jackson's The Hobbit trilogy, Radagast only gets mentioned by name in the novel. But through The Lord of the Rings Appendix and Tolkien's other works, such as The Silmarillion, it's revealed that Radagast was much closer to nature than the other Wizards and mainly concerned himself with the forests and animals of the world.
Wizards did not share the same power, as they all fulfilled different roles within Middle-earth. So, many assume that Radagast's abilities focused on healing plants and keeping nature in check. Living along the outskirts of Mirkwood, he was also said to be wiser than any man when it came to herbs and animals and able to speak many languages.
During The Fellowship of the Ring, the Council of Elrond mentions the whereabouts of Radagast, with Gandalf describing him as a "master of shapes and changes of hue." But the true meaning of Gandalf's words is unknown, with some fans believing it refers to the illusionary magics that can mess with the mind, whereas others think it refers to the growing of plants.
Regardless, in The Hobbit movies, Radagast holds his own against Sauron's forces, despite not fighting as well as Gandalf. While Radagast's combat abilities never get revealed, it's likely that Peter Jackson's interpretation is somewhat correct, as Wizards were among the most powerful beings to walk Middle-earth. Although, as Tolkien's Unfinished Tales explains, Radagast purposefully chose to avoid fighting in Sauron's war.
It appears Radagast became too obsessed with animals and plants and forsook his mission to oppose Sauron. Because of that, Tolkien wrote that it's unknown if Radagast was allowed to leave Middle-earth with Gandalf and the Elves. However, he believes that Radagast's failure wasn't as bad as Saurman's betrayal, meaning he likely would've been allowed to leave eventually.
Radagast was one of the gentler souls in Middle-earth. Despite being sent to face Sauron, he preferred living within nature and ignoring the goings-on of Middle-earth. He likely honed his skills in protecting the animals and plants of Mirkwood, especially once the War of the Ring began. Unfortunately, the full power of Radagast will likely never come to light.