Nate was given a Plume Fossil by a researcher in Twist Mountain after working to protect it from Kai. He was told that there was a laboratory in Lentimas Town that could revive it.
Upon arriving at the Fossil Research Lab in Take to the Sky!, the scientists there revived Nate's Plume Fossil, turning it into an Archen.
Archen then went on a brief rampage, as he was unfamiliar with his surroundings, but was eventually calmed by Nate. Nate soon learned of Archen's desire to fly and tried to teach it how, but to no avail. Archen then asked to join Nate's team, having grown to trust the Trainer. Nate accepted and caught Archen in a Poké Ball.
Archen was sent out to battle a wild Skorupi in Gateway to Friendship! Archen was initially faced with a disadvantage, as Skorupi used Acupressure to boost its Speed and Defence, making it difficult for Archen to land an attack. Furthermore, due to his inability to fly, Archen was unable to engage with Skorupi when it attacked from up high. Archen then caught a break when he was able to fly briefly in order to avoid Skorupi's powerful Poison Fang, delighting Archen, who then learnt Rock Slide and defeated Skorupi.
In A Windswept Escape!, while battling against a Trainer's Gligar, Archen learnt to use the wind currents to help it fly. It continued training to use this technique until it faced Calvin and his Aerodactyl in The New Rock and Roll! Faced with an opponent far more skilled at flying than him, Archen found himself at a disadvantage. However, Archen and Nate refused to give up and Archen evolved into Archeops. Using its new wings, Archeops was able to keep up with Aerodactyl and eventually defeat it with its newly-learned Sky Attack.
After the battle, having witnessed Archeops' potential, Calvin requested that Nate let Archeops train with him and Aerodactyl. After discussing it with Archeops, Nate agreed and left Archeops with Calvin and continued on his journey.
Archen is a Pokémon that is easily panicked, as seen when he was first revived from the Plume Fossil. Having woken up in an entirely new environment caused Archen to attack the group in its panic. His panicky nature was also seen when he freaked out upon meeting Braviary. Despite this, Archen can be calmed down by Nate, showing that he has a strong connection with him. This strong bond was also seen in The New Rock and Roll!, where Archeops was moved to tears at the thought of leaving Nate.
Archen's greatest desire is to fly, but is unable to properly in his current form, only able to glide for brief periods, despite many lessons from Nate and Braviary. His failure to fly often causes Archen to cry in frustration. This dream was finally realised in The New Rock and Roll!, where it finally evolved into Archeops, allowing it to fly properly.