There is actually a lot more illustrated literature of Pokemon, then just the Pokemon Adventure series. This includes: 

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Pokemon Pocket Monsters series  which contains

Pokemon Pocket Monsters, Pokemon Pocket Monsters Ruby and Sapphire, Pokemon Pocket Monsters DP, Pokemon Pocket Monsters HG/SS, Pokemon Pocket Monsters BW, and Pokemon Pocket Monsters X/Y. In all of these, Red is the main protagonist, and in all of these, Clefairy is his main Pokemon, like Ash's was originally going to be in the anime.

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Pocket Monsters Zensho series

Pocket Monsters Zensho and the like, I don't know much about this one, except for the fact Red is the main protagonist. 

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Pokemon Gold and Silver: The Golden Boys series

This was a manga adaption of the games Pokemon Gold and Silver, but sadly they cancelled it before any climax happened in the story.

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Pokemon Battle Frontier series

This manga, named Pocket Monsters Emerald: Challenge!! Battle Frontier in Japanese, features a boy named Enta being invited to the Battle Frontier by Scott, and is later mentored by Rald (Emerald, although his appearance matches Ruby)

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Pokemon Diamond and Pearl Adventure! series

This one I know a lot about, since I have read it, and I own the series, (except for the Japanese only releases of course) that follows the adventures of a boy named Hareta, who is loosely based off of Diamond, (think Diamond, but shorter, but not as short as Emerald) who teams up with Mitsumi (Platinum or Dawn's appearance), and travel through Sinnoh to fill the PokeDex, as well as find Deoxys and fight off Team Galactic.

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Pocket Monsters HGSS Jou's Big Adventure series

This follows the adventure of Jou, whose appearance matches Gold for the most part.  It's all about his adventure through Johto.

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Be a Pokemon Master!! BW series

A series based off the Pokemon Black and White games, promoted by CoroCoro as a 'walkthrough comic.'

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Pocket Monster BW: The Heroes of Fire and Thunder series

A series of mangas promoted by CoroCoro, which is based off the Black and White games, but not as a walkthrough comic. Although I have not read this series, I can inference 'The Heroes of Fire and Thunder' to be based off the types of Reshiram and Zekrom.

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Pocket Monsters BW: Good Partners

This was a manga based off the Black and White games, that was covered all in one volume. 

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Pocket Monsters B2 W2: A New Legend series 

A manga series about Arata's (appearance based off of Lack-Two, or the male character from BW2) adventures through Unova.

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Pokemon Mystery Dungeon: Genji's Rescue Team series

This is about a boy named Genji, who was transformed into a Torchic and formed a Rescue Team with a Mudkip. This is nearly a direct copy of the games, but the ending was very different.

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Pokemon Mystery Dungeon: Blazing Exploration Team series

This was a manga version of the great Pokemon Mystery Dungeon: Explorers of Time/Darkness. 

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Pokemon Colliseum Snatcher Leo series

A manga based off the Pokemon Colliseum spin-off series..

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Pokemon Colliseum Snatchers! series

Another manga based off Pokemon Colliseum's storyline.

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And there are tons more for you to check out! I mean TONS. Like ones based off the anime, (who's protagonist is Red, though) the Pokemon Rangers series, and more!

This is Umbreon-kun signing out!

~ @UltimateUmbreon