Digimon World DS features rather unusual Digivolution lines for some of its Digimon; Many Digimon have digivolution lines that do not correspond with established lines in other media. The digivolution lines in Digimon World DS and other Digimon media are equally vaild as Digimon do not have set evolutions as Pokémon do, rather suggested lines that are logical upgraded forms.
- Impmon cannot digivolve to Beelzemon, his true Mega form as shown in Digimon Tamers (Infermon digivolves into Beelzemon.).
- Poyomon along with several other Fresh level Digimon are In-Training level in the game, and digivolve into Rookie level Digimon. Because of this, Poyomon can digivolve into either Gomamon, Crabmon, or Kamemon (all of which are Aquan types, unlike the rest of Poyomon's normal evolutionary line Patamon (Bird), and Angemon through Seraphimon (Holy)).
- Leomon does not have SaberLeomon as a mega form (Rapidmon gets that honor), instead he digivolves into Monzaemon who can then digivolve into BantyoLeomon.
- Cyberdramon cannot digivolve into Justimon (but SuperStarmon can). Instead, it digivolves into Ghoulmon Black.
- Zudomon digivolves into Vikemon, instead of Plesiomon, (As Vikemon's previous form, Shakkoumon, is absent from the game). Instead, Whamon digivolves into Plesiomon.
- Angewomon digivolves into MarineAngemon instead of Ophanimon or Magnadramon, although Ophanimon is an NPC in the game. Magnadramon is absent from the game.
- Gekomon cannot digivolve into ShogunGekomon, because ShogunGekomon only appears as a non-obtainable boss. Instead, Gekomon digivolves into Whamon.
There is a possible reason as to why ShineGreymon, MirageGaogamon, and Ravemon aren't in the game, and in Digimon World: Dawn and Dusk. The protagonist in Digimon World DS uses a Digivice IC, and in the anime, the Digivice IC couldn't hold the power of the Mega level digimon. In Digimon World Dawn/Dusk, the protagonist uses a Digivice Burst, which is capable of handling the Mega level digimon, in addition to their Burst Modes.