Over the many years that Pokémon has been around, there have been many fascinating aspects to the species represented by that name. One of them is how it is apparent that some species seem to be apparently made up of other species, in whole or in part. It's something to highlight and discuss, given how there have been many more examples of them since that time, seemingly making this an "ingrained" design of sorts.
A noticeable one for many fans is how three Magnemite make up a Magneton, virtually unchanged in appearance and seemingly only held by the power of magnetic attraction. The latter species still has a single mind and is therefore united as such, not to be considered as the separate components that it seems to be made up of. It is an exemplary representative of this aspect and possibly the oddest as well.
Similarly but less odd is how three Diglett appear to make up a Dugtrio, with a similar case applying to the later appearing Wiglett and Wugtrio. The case may be deemed to be less odd here since they seem to share (and be connected to) the same internals - much like Beldum and its family, which are not under consideration here - rather than being simply "attached" as in the previous case of Magnemite and Magneton.
More recently, there is the Dreepy species family, whose later evolved forms (Drakloak and Dragapult) also contain a "mini-Dreepy" - two in the case of the latter - that are as much a part of them as their expected main bodies are. The lore states that these "mini-Dreepy" are being reared until they can stand as real Dreepy on their own, which does seem to make sense given that they are partial Ghost types and thus developmental "apparitions".
In a sense, the evolved forms of Slowpoke can be considered to be made up of two different Pokémon, as the shell part according to lore is a highly transformed Shellder, for which the appearances are different according to form and species. The role of that Shellder had been "planned" to be "fleshed out" according to the beta version of the second generation games, but that didn't happen, so at least for now the lore still serves the explanatory purpose.
Whether or not the apparently disparate parts of certain Pokémon species, which look like other and/or related species, have a bearing on the constitution of those species as a whole, having them seemingly integrated into those species makes for an insightful consideration of how the species manifest themselves in design and appearance - not to mention lore. Even such a repetitive design and appearance seems to have much to convey.
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