Weezing

Magneton are three Magnemite stuck together and Dugtrio are three Diglett poking out of the same hole; here, two Koffing have fused into one. The Pokédex treats it as an anomaly rather than normal growth: on rare occasions, a mutation occurs and two small balloons end up joined together. It isn't a body that matures; it's a body that duplicates.

The two spheres are tied together by a tube and work in shifts. When one inflates, the other deflates, and that back-and-forth motion mixes the gases each head stores separately. The more it mixes them, the more toxic and rotten the whole thing becomes. The large head has pronounced eyebrows and fangs jutting from its lower jaw; the small one barely has a face.

It eats garbage, and that's not a metaphor: germs, dust, and the gases released by whatever gets left lying around in a kitchen. It looks for dirty, neglected houses to settle in, then waits for the owners to fall asleep before heading down to the trash can. Its official habitat is urban, something almost no Pokémon from the first generation can claim.

It is 1.2 meters tall and weighs 9.5 kilograms. Two balls that size weighing less than a small dog, because there's nothing inside but gas. It closes out the Koffing line, which stays at two stages.

490 points distributed very badly. Its 120 Defense is the only standout, while 70 Special Defense and 65 HP make for a short-lived base on something that wants to take hits. Its 60 Speed leaves it moving last against almost anything, and neither 90 Attack nor 85 Special Attack is enough to break anything through sheer force.

The interesting part is its abilities. Levitate cancels out its weakness to Ground, and since it is pure Poison, that leaves it with a single red box on the entire chart: Psychic. With Fighting, Poison, Bug, Grass, and Fairy resisted, there are plenty of attacks it can switch into without thinking.

Neutralizing Gas does something different. As long as it is on the field, no other ability works: Multiscale, Intimidate, Water Absorb, all shut off until it leaves. The price is giving up Levitate and becoming vulnerable to any Ground attack again.

The moves support the defensive plan. Will-O-Wisp by TM burns any physical attacker that comes to knock it out; Toxic Spikes, also by TM, sets the hazard and clears it on entry because it is Poison-type; Sludge Bomb at level 32 and Gunk Shot by TM are its real attacks. Pain Split shares those scarce HP with the opponent. And when there is nothing left, Explosion at level 50 hits with 250 power and Destiny Bond at 62 takes someone down with it.

In a normal playthrough, it works well: it joins the team halfway through the adventure and takes physical hits while the poison does its job. Against fast special attackers, there is nothing it can do, because with 65 HP and 70 Special Defense it goes down before it gets to move.

Amorphous Egg Group, the drawer for creatures with no fixed shape — gases, slime, ghosts. The gender split is clean, half male and half female, so breeding does not depend on finding the rare sex.

It takes 20 incubation cycles, around 5355 steps. The Egg Move list is empty: it inherits nothing, and everything it knows comes from leveling up or TMs. That simplifies breeding down to a matter of stats and nature.

The evolution is just as straightforward. Koffing levels up to level 35 and that's it: no stones, no friendship, no time of day. The only variation is which region the Koffing comes from, since that determines whether it becomes the Galarian form instead of the Kantonian one.

Its catch rate is 60, in the lower half of the scale. Neither the triviality of a 255 on Route 1 nor the long fight of a 45, but it is worth lowering its HP before throwing anything. In the wild, it may be holding a Smoke Ball, the item that guarantees escape from any battle against a wild Pokémon.

Defeating it gives 2 effort points in Defense, exactly its best stat, and 172 base experience. It grows at a medium pace, without the late-game growth curves of other lines.