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Type effectiveness (ie: super effective, not very effective, etc.) is generally distinguished by a number of factors. These line up, generally, as "practical" and "energy". Practical stuff is the simplest and most intuitive.

What I mean when I say "practical" of course is the actual match-ups. This is mostly seen around the "neutral" types (Normal, Dark, Fighting, Steel, etc.) that lack any strong elemental affinities. The match-ups between these are largely a result of the fighting styles and ideas that are inherent to the individual species. Fighting types are strict, methodical and efficient. This makes them strong against Normal/Dark types, since they're capable of taking advantage of the openings in their more natural attacks. Dark types do poorly against Fighting Types for this reason--the "cheap tricks" inherent to the movepool do poorly against a trained fighter that can recognize them. This kind of situation governs the relationship between most "non-elemental" pairings, or most keenly "pairings in which one party has no strong affinities".

This, to an extent, is also wrapped into the less mundane match-ups. A fire type is weak against water types on a practical basis because the water cools down their bodies, sending them into shock. Simply put, they become hypothermic very easily. This is, of course, also present for Fire vs. Ice; ice types become hyperthermic (heat stroke) very easily.

In other cases, the issue is generally one of "energy", as below.

"Energy" is of course something that's sort of inherent to any magical setting. A Clefable has "fairy energy" within them, which is the source of both their strength (ability to RAZZLE DAZZLE) and weakness (susceptibility to poison). This is generally due to these energies having a disruptive effect on one another. It sends the inner body into turmoil, causing a damage and weakness that seems otherwise implausible.

This energy is also what generally dictates availability and is why most pokemon can't learn moves contrary to their own typing, at least not naturally. TMs imbue this energy and this power, but tend to do so poorly in contrary cases.

Ghost types typically act upon this energy. This is the reason ghost types tend to hurt each other efficiently.

Normal types lack any strong energies, rendering them immune to ghost types. On the same token, however, the lack of energies creates a lack of competition; this is why normal types often have an abnormally wide array of skills. There are no competing forces.

Dragon types are innately resilient to all forms of energy and especially so to a few. Only a dragon type can effectively disrupt one of their kin, at least until the introduction of fairies which act as antithetical agents. Ice types get by on a practical basis, as most dragons are cold-blooded.

Energy is attached to both the soul and the body.

Growth is kind of a tricky subject within the pokeverse. Maturity is dictated by a lot of factors, at least within most media. Experience, chronological age, etc. all have deciding stakes in the biological maturity of any given creature. A pokemon exposed to great stress and great trials will grow (evolve) at a faster rate, but it's inherently the case that growth also has to be an age related function. To that end, I generally view it as a byproduct of both; physical and mental maturity are dictated by both age and experience. The former is especially important in analyzing characters, because age confers not just growth (in the typical organic sense) but also social experience. A pokemon who physically matures quickly through combat will not necessarily be as mentally mature as one who took longer to evolve. However, growth periods (evolution) will still trigger structural changes in the brain that can either cement or alter perception significantly, so it's not purely a one-sided thing. Rather, the two mix with mental growth being primarily age/socialization and physical growth being primarily combat experience. This isn't a linear process though; age tends to be the primary contributor to both very early on.

Also, growth rates are logically probably closer to animal rates, since humans are pretty bloody anomalous. Nuanced mental skills may take a while to develop, but low-level social, mental and physical skills (recognizing predators, acquiring food, mobility, basic speech, etc.) develop fairly quickly out of necessity. This means that there's usually a spike in functionality over the course of the first few weeks (up to the point that I would expect a month-old pokemon to act roughly like a human child) and then the progress would slow until it leveled off. This is in contrast to humans, who tend to build such skills at a fairly linear rate.

Generally, I view the culture of individual species as a byproduct of predation factors. Species that are longer lived and have relatively few predators trend towards more complex cultures. The two sides of the fence tend to be "high selective pressure" and "low selective pressure".

Pokemon with low selective pressure tend to be powerful, bulky herbivores. They're typically no starved for food, they don't have to deal with predation or hunting risks due to it and a looser culture develops because of it. Due to the lack of persistent threats, the pokemon of these species trend towards laxer communities and more frivolous pursuits. This doesn't necessarily mean that they have a complex culture in the contemporary sense, but rather that they generally have a fairly varied one. This might mean something as significant as singing songs and writing poetry or it might be as crude and basic as butting heads and engaging in friendly games (of a more modern sort) in leisure. If necessity is the mother of invention, then these pokemon usually have a necessity to fill their time.

On the other hand, pokemon with high selective pressure tend to be either weaker herbivores or carnivores. Carnivores tend to have relatively fewer leisure activities and a strict, authoritarian leadership system. This is a byproduct of necessity; food is relatively finite and there's always the risk of being attacked back. Strong leaders take control of clans and move them about. Herbivores tend to have a similarly centralized leadership but it's usually dictated by age or some kind of social respect. There's more leisure among these groups, but more complex things (ie: games) tend not to get developed and spread due to the constant threat of others.