Smoochum in depth
Muchul, the kiss and the name
The Japanese ムチュール, Muchul, combines 夢中 (muchū, being engrossed in something) with the チュー that represents the sound of a kiss in Japanese. English was more direct: smooch, to kiss, plus chum, a friend. Both versions point to the same thing, and the design seals it with a humanoid baby head, blond hair with bangs and pink lips that take up more surface area than the eyes. It is one of the few Pokédex lines with no possible male in either of its two stages.
The Odd Egg and other routes
In Gold and Silver, the only way to get one was by breeding Jynx. Crystal added the Odd Egg from the Day Care on Route 34, which could contain any of that generation's baby Pokémon. From the fourth generation onward, it started appearing in the wild: through a swarm in Lake Acuity in Diamond and Pearl, Snowpoint Temple in Platinum, hordes in Frost Cavern in X and Y, the Crown Tundra in Sword and Shield, and the caves of the Grand Underground in the Sinnoh remakes. It's a common pattern among the baby Pokémon introduced in the second generation: they started out confined to the Day Care and were gradually released onto the map over the years.
The level-up list against level 30
There's a decision here that the game never explains. The learnset continues beyond level 30, but evolution happens right there, and normally a trainer will never see the upper half: Psychic at 32, Sweet Kiss at 36, Mean Look at 40, Perish Song at 44 and Blizzard at 48. Anyone who wants those five has to cancel evolution five times in a row and drag an 18-level stretch around with 15 Defense. Perish Song is the most striking case, because after three turns it takes both participants out, and a baby with 45 HP doesn't have much to lose in that trade.
The early part is genuinely weak. Pound and Lick at level 1, Powder Snow at 4, Confusion at 12; until Ice Punch at 28, there is nothing above 60 power, and that move is physical. The interesting block is the group of status moves spread between 8 and 24 — Copycat, Sing and Fake Tears — which is where a fragile creature can steal a turn.
Three babies from the same batch
Gold and Silver invented pre-evolutions for three Kanto species that previously had nowhere to come from, and Smoochum arrived alongside Elekid and Magby. Of the three, it is the only one with its stat distribution tilted entirely to one side: the other two split their two attacking stats almost evenly, while it is left with 30 Attack against 85 Special Attack, a gap of nearly three to one. The adult form inherits the same problem and solves it with much higher Speed and Special Attack, something that doesn't happen here. Covet, at level 16, is its neatest detail: it eats the Berry it is holding, which in the wild is specifically an Aspear Berry.