Cleffa in depth
The note Clefairy is missing
In Japanese, its name is ピィ (Py), a shortened form of ピッピ (Pippi), Clefairy's Japanese name. All three members of the family share that sound. Outside Japan, the game is musical: “clef” is the sign at the start of a stave and “fa” is the note, with the same clef that opens Clefairy's and Clefable's names. The whole line is named after solfège.
The design starts with the shape: a five-pointed star with a face. The Pokédex entries build the mythology on top of that outline —the meteorite, the reincarnated star, the nocturnal dance—, while the curl on its forehead and pointed ears are direct inheritances from Clefairy, which was already in the 1996 games.
The day it stopped being Normal
From Gold and Silver through Generation V, it was a Normal type. Generation VI changed it to Fairy along with the rest of the line, and the change is not merely cosmetic: as a Normal type it was immune to Ghost and only feared Fighting; as a Fairy type it resists Fighting, Bug and Dark, is immune to Dragon and gains two new weaknesses, Poison and Steel. For a body with 28 Defense, the practical difference is small, but Disarming Voice, which it learns at level 12, gained Same-Type Attack Bonus, and Drain Kiss, Dazzling Gleam and Play Rough joined its repertoire, none of which existed before.
The other generational detail is its ability. Up to Generation V, this line was the only one in the entire Pokédex that could have Magic Guard; today, a handful of species share it, several of them considerably better.
Eight moves and then nothing
Its level-up moveset has eight entries and ends at level 20: Pound, Splash and Copycat to start with, Sing at level 4, Sweet Kiss at level 8, Disarming Voice at level 12, Encore at level 16 and Charm at level 20. The fact that Splash, a move that does absolutely nothing, is one of the three moves it starts with says a lot about its intentions. Copycat repeats the last move used by the opponent, which with 15 Speed means it always goes second.
From level 20 onwards, everything it learns comes from TMs, and the list expands sharply: Flamethrower, Fire Blast, Psychic, Solar Beam, Shadow Ball, Dig and Uproar. It is the legacy of a line that has always learned a bit of everything. With 45 Special Attack and 25 Attack, none of those moves justifies spending a TM on it. The one worth teaching it is Metronome, which does not win games but has been the family's signature move since Generation I, and in the hands of something this slow it produces memorable turns in either direction.
Light Screen and Reflect also appear, and together with Friend Guard they form the only team-support role Cleffa can fulfil in doubles before it goes down.
The Crystal Egg
In Pokémon Crystal, the Day-Care Man on Route 34 handed over an Odd Egg, and Cleffa was one of the baby Pokémon that could hatch from it. Those eggs had a much higher chance of producing a Shiny Pokémon than normal, and for years they were the practical way to get a differently coloured one without chains or counters.
It appears in the wild in few places and is almost always associated with altitude: Mt. Coronet and the Trophy Garden in Generation IV, and Mount Hokulani at night in Generation VII. Its story matches Igglybuff: a baby Pokémon from Generation II, an evolution by friendship and a Fairy type gained in Generation VI. Both lines eventually require a Moon Stone for their final stage, so a Trainer raising both ends up fighting over the same stone. Defeating it awards 44 base experience points and a single effort point in Special Defense.