I've come across a few videogame categories that should be merged together. First are duplicate categories for the same game:

• "Digimon Battle" and "Digimon RPG" are the same game, the latter being the title of the current English release.
• "Digimon World 2003" and "Digimon World 3" refer to the same game; the title change was a region difference. Should merge and rename to "Digimon World 3 / Digimon World 2003".
• There are two categories named "Digimon" when I search for them, one with a cover and one without, not sure if that's a bug or something that needs to be merged.

And next are some categories that can be consolidated to enhance viewership, in the same way that "Pokémon FireRed/LeafGreen" is one category rather than two:

• "Digimon World Dawn" and "Digimon World Dusk" are two versions of the same game ala Pokémon, should be "Digimon World Dawn/Dusk".
• "Digimon Adventure: Anode Tamer", "Digimon Adventure: Cathode Tamer" and "Digimon Anode/Cathode Tamer: Veedramon Version" are all versions and rereleases of the same games, and should be merged and titled "Digimon Adventure: Anode/Cathode Tamer".
• "Digimon Story: Super Xros Wars Red" and "Digimon Story: Super Xros Wars Blue" should be merged into the existing category "Digimon Story Super Xros Wars Blue/Red", though that one should have a colon added to match.
• "Monster Rancher 1 DX" should be merged into "Monster Rancher", as it is a rerelease of that game, and I often see people streaming the DX version under the original version's category, and sometimes the reverse.
• "Monster Rancher 2 DX" should be merged into "Monster Rancher 2", same reason as above.

Edit: Several of the changes I suggested have been implemented since I made this suggestion, so I'll move them to the bottom of the post for posterity.

Duplicates:
- "Digimon Universe: App Monsters Cyber Arena" was the name of the demo version of "Digimon Universe: Appli Monsters", and should be merged into it the latter category.
- "Monster Rancher Battle Card GB" and "Monster Rancher - Battle Card" refer to the same game. The first one is the correct title.

And lastly, some categories to rename:
- "Digimon: New Generation" was released with the title "Digimon New Century".
- "Digimon Story Cyber Sleuth" should have a colon after Story.