The cry quiz is the Pokédle game I am worst at by a wide margin. I can usually name a Pokémon from a tiny image crop. I cannot, apparently, tell Krabby from Voltorb by sound alone. After a few weeks of getting humbled I started paying actual attention to what was going on, and a handful of things became obvious.
Why the old cries sound interchangeable
Gen 1 and Gen 2 cries were generated on the Game Boy and Game Boy Color sound chip. Four channels, almost no memory, 251 cries to fit on a cartridge. They were built from a small set of square-wave components that got pitched and stretched and layered. So Krabby, Drowzee and Voltorb genuinely do share a timbre. They differ mostly in pitch curve and length.
Two practical things follow from that. Do not try to remember the whole cry as a single sound. Remember the shape. Does it rise, fall, stay flat, warble? And pay attention to length. Tiny mons (Caterpie, Pidgey) get sub-half-second blips. Big slow mons (Snorlax, Lapras, Onix) get drawn out cries that go on for almost two seconds.
Five rough families that cover most Gen 1
These are not official categories. They are buckets I made up because they kept showing up.
Short flat chirp, under a second. Pidgey, Rattata, Spearow, Sentret. If the cry is over before you register it, guess one of these.
Falling growl. Long, harsh start, pitches down. Onix, Rhydon, Gyarados, Aerodactyl. Mostly the big physical mons.
Rising whine. Starts low, ramps, often a buzz at the end. Voltorb, Magnemite, Porygon. Basically diagnostic of Electric or Steel in Gen 1.
Two or three note melody. Pleasant, almost musical. Jigglypuff is the obvious one. Chansey, Clefairy, Snubbull. Pink mons, basically.
Static burst. Harsh, noisy, no real pitch shape. Tangela, Exeggcute, Weezing, Muk. The gross ones.
Modern cries are higher fidelity, which is a trap
From Gen 5 onward the cries were re-recorded, sometimes with real instruments or vocal samples. If you already know the Pokémon, this is great. If you do not, the extra detail actually makes it harder to compare against your memory of the older sprites. Galarian Yamask sounds nothing like Yamask.
Useful side effect though. If the cry sounds like a real animal (a bleat, a trill, a yip), it is almost certainly Gen 5 or later. That cuts your pool in half right away.
A boring practice routine that works
Ten minutes a few times a week is plenty. Play the cry quiz in Unlimited and, after every guess, right or wrong, replay the cry once while looking at the answer. Sound, name, sound. That is the loop that builds the association. Passive listening did almost nothing for me.
The other thing worth doing once: pick one of the families above and listen through every Pokémon in it back to back on the PokéAPI cry endpoint or Bulbapedia. Five minutes of that and the differences inside the family stop sounding subtle.
The cries I personally always miss
Tangela, which I read as Weezing every single time. Slowpoke, because sometimes it is actually Slowking. Magcargo, which I confuse with anything slug-shaped. The entire Voltorb / Magnemite / Porygon rising-whine cluster.
If you spend one focused session on those five your daily accuracy will jump within a week. The cry quiz rewards narrow practice more than any other Pokédle game I have played.