Prior to the start of the series Nana was given to Ruby as a Poochyena as a gift from his father, Norman. One day when Ruby was playing with Sapphire a Salamence attacked them. Ruby sent out Nana, Kiki, and Rara to fend it off. The three managed to scare it away, but Ruby got injured in the process, which scared Sapphire. Because of this incident Ruby decided to never battle in front of people again.
Nana first appeared as a Poochyena in Creeping Past Cacnea, where she was seen with Ruby on his trip to Hoenn. After running away from home Ruby runs into Professor Birch being attacked by two Mightyena. Ruby decides to battle the Mightyena, and sends out Nana and has her use Leer. The move doesn't do anything due to Ruby caring only about appearances and the Mightyena pounce on them again, causing Ruby to fall off a cliff.
In Guile from Mawile, Ruby went into Granite Cave in order to find a Milotic. During the trip he is attacked by a group of Mawile and in the fight Nana and Kiki both evolve.
In Hanging Around With Slaking I, Nana is used to fight alongside Kiki against Norman and his Slaking and Delcatty. Nana fired a Hyper Beam while Kiki attacked with Iron Tail. Despite their strength, Kiki and Nana were easily swept away due to the fact that Norman knew all of Ruby's strategies, as he was the one to teach them to him.
In Mind-Boggling with Medicham, Nana is used to advance Ruby through the Normal Rank of the Cool Contest. In Going to Eleven with Loudred & Exploud I, Nana is used alongside Ruby's other Pokémon to battle against Courtney and her Ninetales. Although Ruby had a five to one advantage his team was beaten due to Ninetales having control of nine different fireballs.
In I More Than Like You, Luvdisc I, Nana is used to advance Ruby through the Super Rank of the Cool Contest. After the contest Nana is used in Ruby's battle against Wallace alongside the rest of team, bar Feefee, and loses. In I'm Always Grumpig First Thing in the Morning I, Nana is sent out to protect Sapphire while being attacked by a herd of Grumpig, and accidentally reveals to Sapphire Ruby's true strength by knocking out all twelve of them with one move.
In Always Keep Whiscash on You for Emergencies, Nana is used to advance Ruby through the Hyper Rank of the Cool Contest.
In The Beginning of the End with Kyogre & Groudon X, Nana, alongside Ruby and Sapphire's other Pokémon, are used to battle against Archie and Maxie. Nana was seen charging at Maxie's Camerupt, but was pushed back by Eruption.
In It All Ends Now VIII, Nana is shown to have won the Master Rank of the Cool Contest, wearing a Red Scarf.