For games that are like Pokemon:
Monster Rancher Advance (USA) GBA ROM Languages: English. For the GameBoy Advance.
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Monster Rancher Advance 2 (USA) GBA ROM Languages: English. For the GameBoy Advance.
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Both of the Monster Rancher Advance, it's like playing Monster Rancher 2 on the go!
Medabots: Metabee Version (USA) GBA ROM Languages: English. For the GameBoy Advance.
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Medabots: Rokusho Version (USA) GBA ROM Languages: English. For the GameBoy Advance.
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Medabots, avoid either Medabots AX games, as they are not RPGs and are just mediocre Smash clones. Also, avoid the new Medabots survivor on IOS, just throwing that out there....
Medarot 3: Kabuto/Kuwagata Version (English Patched) GBC ROM Languages: English Patched, Japanese. For the GameBoy Color.
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Medarot: Kabuto Version (English Patched) GB ROM Languages: English Patched, Japanese. For GameBoy.
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Medarot: Kuwagata Version (English Patched) GB ROM Languages: English Patched, Japanese. For GameBoy.
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The GBA Medabots are actually udated remakes of Medabots 2 for the GBC (kind of like FRLG). Unfortunately, 2 doesn't have an englich patch I think, so you'll have to stick with the 1st and 3rd ones when it comes to GBC medabots.
Telefang: Speed Version (English Patched) GBC ROM Languages: English Patched, Japanese. For the GameBoy Color.
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Telefang: Power Version (English Patched) GBC ROM Languages: English Patched, Japanese. For the GameBoy Color.
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Telefang 2: Power Version (English Patched) GBA ROM Languages: English Patched. For the GameBoy Advance.
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The Telefang, as close as you can get to Pokemon without being Pokemon. So much so, it was actually repurposed into a several notorious Chinese bootlegs, such as the infamous "Pokemon: Jade Version". You collect monsters by getting their phone numbers and literally "calling" them into battle.
Robopon: Sun Version (USA) GBC ROM Languages: English. For the GameBoy Color.
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Robopon 2 - Ring Version (USA) GBA ROM Languages: English. For the GameBoy Advance.
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Robopon 2 - Cross Version (USA) GBA ROM Languages: English. For the GameBoy Advance.
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Robopon was also the victim of being bootlegged into a fake Pokemon game back in the day, and is themed around robot. The advance games are more unique mechanically then the GBC ones.
Metal Walker (USA) GBC ROM Languages: English. For the GameBoy Color.
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Not quite an RPG, and is actually similar to games like Breakout or Pinball with RPG elements. Capcom's foray into CCRPGs, also focuses on Robots like Medabots and Robopon.
Azure Dreams (USA) GBC ROM Languages: English. For the GameBoy Color.
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Mystery dungeon style RPG with Roguelike elements. A port of the PS1 game with signicantly less droning music.
Dragon Warrior Monsters (USA, Europe) GBC ROM Languages: English. For the GameBoy Color.
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Dragon Warrior Monsters 2: Cobi's Journey (USA) GBC ROM Languages: English. For the GameBoy Color.
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Dragon Warrior Monsters 2: Tara's Adventure (USA) GBC ROM Languages: English. For the GameBoy Color.
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A lovely dungeon crawler using Akira Toriyama's creature designs from the Dragon Quest series. Very familiar if you've played the core franchise, but uses a fusion system similar to Shin Megami Tensei.
Shin Megami Tensei: DemiKids Dark Version (USA) GBA ROM Languages: English. For the GameBoy Advance.
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Shin Megami Tensei: DemiKids Light Version (USA) GBA ROM Languages: English. For the GameBoy Advance.
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Shin Megami Tensei: Devil Children: Kuro no Sho (J+English Patched) GBC ROM Languages: English Patched, Japanese. For the GameBoy Color.
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A more child friendly spin off of the often apocalyptic Shin Megami Tensei franchise. Much like Dragon Quest Monsters, it's very similar to it's host series, but everything is just a lot more cuddly.
I could go on, and on, and on, and on, and on, and on, and on, and on, and on, and on, and....
But the tragic thing is, a lot of these kinds of games never became localized, or are simply not well known or popular enough to recieve fantranslations (such as Chocovaders, Snapkids, ZokZokHeroes, Granbo etc.).