Despite their vast tonal differences, the Shin Megami Tensei and Pokémon series exist as something akin to video game siblings. Both role-playing franchises place a huge emphasis on capturing monsters to turn into allies, which then level up and learn new skills or evolve into more powerful forms. Sometimes, people will even refer to MegaTen as a big ol' Pokémon rip-off, because they're young and foolish and have no comprehension of video game history.
And while the specifics of monster-capturing vary from series to series, the two franchises really do play a lot alike in many ways. Shin Megami Tensei IV in particular has drilled home this fact to me as the limitations of my party members' capacity for learning new skills is sharply limited, just like in Pokémon. A key element of Pokémon's long-term strategy comes from the fact that each of your creatures can only know four skills at any given time, and learning new abilities comes with a price: You have to discard an old one to make room.
SMTIV takes a similar tack, though it optionally allows you to expand your allies' capacity with "App Points" that you earn each time your protagonist levels up and can be expended on any number of supplemental skills. Is it more important to be able to speak esoteric demon languages and recruit otherwise inaccessible creatures, or would you rather the creatures you collect have access to more powers? Ultimately, every choice you make requires a trade-off, which of course is a big part of Pokémon's appeal as well.
Still, there's a fundamental difference between the demons you capture in SMTIV and the monsters you collect in Pokémon. The latter tends to whitewash the nature of the creatures' captivity: You're beating them up and imprisoning them in a special capsule prison, then calling them out to fight on your behalf. It sounds pretty dreadful, but Nintendo's kid-friendly localization makes it seem like you're actually a pretty swell person doing the creatures a favor, and they all become your friends. Basically, you're not meant to think about it too hard.
MegaTen makes no such pretense. You're battling demons, angels, and ghosts: Other-dimensional creatures openly hostile to humanity. But instead of capturing them, you form pacts with them. Demonic contracts, basically. This can be as simple as saying the right thing at the right time, or as complex as making great sacrifices while navigating a complex conversation and hoping not to irritate the demon at hand. Still, all the demons you team up with join you consensually, which actually makes its eldritch universe friendlier than Pokémon's when you stop and think about it.
If you really look, though, you'll find an even more significant difference in the way the two series actually expect you to deal with the allies you make. Pokémon fosters a sort of collector's mentality; you can only have six pokémon with you at a time, sure, but you can dump a few hundred in the PC to call up at will (or simply to arrange in numeric order and weep for your misplaced priorities when you've completed the entire pokédex). Pokémon evolve and grow stronger, and the overall intention seems to be for players to stick with a few favorites (particularly their starter) and move alternate pokémon into and out of the party as needed.
SMTIV makes this approach impossible. You don't have demon storage, so you're limited to retaining the demons you have on-hand. As with skill slots, you can invest App Points to add more spaces for demons in your team, though of course your active combat party is limited to four participants. Even at your maximum team size, though, you can only run with a couple dozen demons (probably less; I haven't maxed out that aspect of my party yet).
There's no pretense, therefore, of these creatures being your friends. They're meant to be fodder, pure and simple. Once you've they've reached a certain level threshold -- usually quite a low one -- they'll have learned all the skills they can inherently acquire. At that point, they offer to pass their skills along to the protagonist, and... that's it. They can still level up, but barring a handful of demons that evolve into new forms, they won't grow any further.
Instead, you're meant to fuse full-grown demons into new ones. SMTIV offers remarkable depth and flexibility with fusions, granting you total control over which powers a new demon will carry over from its "parents" -- which can be incredibly useful once you start learning passive elemental resistances. There's nothing quite like passing, for example, the Resist Ice attribute to a demon whose only innate weakness is ice. But in the process of fusion, the original demons are completely destroyed. It's not like Pokémon, where you can leave certain monsters together at the farm and the day care coordinator will mysteriously discover an egg.
The interesting thing about fusion's destructive nature is that the demons seem totally aware of it. In the course of negotiating to convince a demon to join your team, they'll often retort with a remark along the lines of, "You just want to use me for fusions, don't you?" Others seem more stoic about it. Occasionally, cute female demons will demand you not fuse them with ugly demons.
In any case, those demons vanish forever... though you can register and re-summon them from the Demon Compendium and they'll reappear just as they were before fusion. So maybe you're not meant to think about the logistics of fusion, either. But because MegaTen is so dialogue-driven (even making conversations a viable combat tactic), I can't help but dwell on the underlying considerations that lurks behind the series' plot from time to time.
People tend to deride video game narratives, and perhaps rightly so. But the nuances of story and tone help distinguish the very similar mechanics of the Pokémon and MegaTen games, making them feel explicitly different... even if you're ultimately managing the same resources and limitations. Kind of makes you wonder why Nintendo decided to throw Fire Emblem into the MegaTen crossover blender instead of Pokémon, though.