TV-Series
Description
The Pokédex (Rotom Dex) is a main character in the anime series Pokémon Sun & Moon, where it serves as Ash's personal Pokédex throughout his journey in the Alola region. It is a Rotom, an Electric and Ghost-type Pokémon that has taken up residence inside a specially designed Pokédex device. This particular Rotom was placed into the device by Professor Kukui, who wanted to create the most efficient Pokédex possible, and the result is a talking, self-learning encyclopedia that accompanies its trainer rather than remaining a passive tool. While it outwardly presents itself as a piece of technology, it is a living creature with its own thoughts, feelings, and habits.

In terms of background, the Rotom Dex is unique among Pokédex models because it contains an actual Pokémon rather than just software. Rotom, as a species, has the natural ability to inhabit electronic devices, and this one was given a purpose beyond mischief by becoming an interactive guide. It claims to be a self-learning Pokédex, similar to an artificial intelligence, and it is capable of speaking human language fluently. It constantly gathers new information during the group's travels and updates its own database, which means its knowledge grows alongside the experiences it shares with Ash and his friends. Its speech is frequently marked by a distinctive verbal tic, as it tends to add the syllable "Roto" to the beginning or end of its expressions and greetings.

Personality-wise, the Rotom Dex is enthusiastic, talkative, and eager to be useful, but it also has a mischievous streak that reflects its nature as a Rotom. In the early part of the series, it develops a persistent habit of getting up close and personal with wild Pokémon in order to confirm whether the information it holds is accurate. This well-intentioned curiosity often backfires, because invading the personal space of wild Pokémon tends to annoy them, and the Rotom Dex frequently ends up on the receiving end of an attack. It is also inclined to announce things in a dramatic and energetic manner, and it takes clear pride in its role as a guide. Despite its occasional overenthusiasm, it is dependable and genuinely invested in helping its companions succeed.

The Rotom Dex's primary motivation is to fulfill its function as a Pokédex while also being a supportive companion to its trainer. It is driven by a desire to gather complete and correct information about the Pokémon of Alola, and it treats every new encounter as an opportunity to learn. It is also motivated by a sense of camaraderie, as it wants to be a helpful presence rather than a mere device. This shows in how it proactively assists the group in the field, such as when it informs them of the percentage chance of encountering certain Pokémon in an area or provides descriptions of unfamiliar species like Mimikyu and Bewear. Its role in the story is therefore twofold: it serves as the source of encyclopedic knowledge that the characters rely on, and it functions as a traveling companion who participates in the group's adventures and adds its own voice to the events unfolding around them.

In terms of key relationships, the Rotom Dex is closely tied to Ash, who carries it and treats it as a partner rather than just equipment. It is also connected to Professor Kukui, its creator and the one who gave it a home inside the Pokédex device. Through its time with Ash, it comes to interact regularly with Ash's Pokémon and his classmates, and it becomes a familiar presence within the group. Its relationships are shaped by its habit of observing Pokémon at close range, which sometimes puts it at odds with the very creatures it is trying to document, but it generally maintains a friendly and well-meaning rapport with those around it.

Over the course of the series, the Rotom Dex experiences development as it refines its behavior and deepens its bond with its trainer. Its early tendency to hover too close to Pokémon gradually becomes less troublesome as it learns from repeated encounters, and its database becomes more robust as it records the many species that the group meets across Alola. It grows from a device that occasionally causes problems through its eagerness into a more dependable and seasoned companion, all while retaining the energetic personality that defines it.

As for notable abilities, the Rotom Dex can speak and understand human language, allowing it to communicate directly with its trainer and the rest of the group. Being a Rotom, it is fundamentally an Electric and Ghost-type Pokémon, and its ability to inhabit the Pokédex device is itself a demonstration of the species' power to possess electronics. It possesses an extensive, ever-expanding store of Pokémon data and can recall and present that information on demand, often with added commentary. It is also capable of functioning as a navigational and advisory tool, offering guidance on where to go and what to expect, and it can make real-time observations about the environment and the creatures within it. Altogether, the Pokédex (Rotom Dex) stands out as a living, talkative, and increasingly knowledgeable member of the Sun & Moon cast, blending the role of technological assistant with the personality of a genuine character.