Silver

Chikorita: Its nice-smelling leaf has the ability to probe its surroundings.
Bayleef: Smelling the pleasant, spice-like aroma that emanates from around its neck causes one to feel hungry.
Quagsire: same
Sunkern: Asserted as fact rather than "it is said"
Sunflora: When the sun goes down, it closes its petals and stands still. Without light, it is not active.
Sentret: same
Lanturn: same (wrong name here)
Aipom: Lives high up in trees. When it jumps from branch to branch, it deftly uses its tail to keep its balance.
Wooper: When on land, a poison-infused mucous membrane is excreted. (wrong name here)
Espeon: By utilizing its 4 ears, even with its eyes closed, it knows all that occurs around it. // this is fuckin badass and the final version is hella watered down
Umbreon: same
Furret: It digs through the ground and makes a tight nest that only it can enter. It goes in tail-first.
Misdreavus: When it feels as if the hair on the back of your head is being pulled, a Norowara has appeared behind you. // Still named Norowara, which apparently turned into Misdreavus, since this is very similar to the Silver Dex entry. Neat.
Unown: same
Wobbuffet: It hides away in dark places. It doesn't make attacks on its own, but when counterattacking, it returns damage threefold. // Still called Twinz. "Shadow Pokemon". Wow, Wobbuffet (body and tail) started out from a Girafarig prevo?
Girafarig: same
Pineco: same
Shuckle: At some point, it works its way into a pot. What its true body is like is unknown. // lmao"potpot" is literally a pokemon in a pot
Dunsparce: It is very persistent. Once it decides on a target, it follows it to the ends of the earth. // fuckin badass
Steelix: Compressed by the weight of the ground, it has come to possesses a hardness that far surpasses that of diamond. // similar to gold final
Snubbull: same
Granbull: If it senses a smell that it has not smelled before, it lets out a low roar.
Scizor: Due to its fondness for shores, it is thought to be a species close to those like Krabby. // ??? lol
Forretress: It eats all kinds of tree bark. It sticks the leftovers onto its shell and makes its shell sturdy. (wrong name here) // also "bagworm pokemon" like pineco above
Heracross: same
Sneasel: same // here "weasel pokemon"
Teddiursa: It's skilled at climbing trees. It picks berries in high places and eats them before they fall down.
Ursaring: It is unsurpassed in its ability to discern smells and is always walking around while having its nose stuck out.
Magcargo: It has a lava-like body, but, for some reason, when it basks in the sun, its skin hardens.
Corsola: In order to protect the carefully-raised tip of its head from being eaten by Staryu, it lives in groups.
Swinub: same
Piloswine: Both of its eyes are covered in fur, but, relying on sound, it acquires its target and rams towards it in a beeline. // "pig boar pokemon" like swinub
Slugma: same
Remoraid: same, but it mentions Mantine by current name of Hane'ei // both are "Jet Pokemon"; final game has "funsha (Jet, but in Japanese and not a transliteration) Pokemon"
Octillery: very close, but "crawls into" rather than "steals"
Hoothoot: same
Delibird: same
Mantine: uses slightly different word for ocean (おおうなばら vs. final ひろい　うみ) but otherwise same // "Hane'ei"
Skarmory: Because its nest is located in a high-up area where violent wind rages, its skin has steadily become harder. // "Yoroidori"
Houndour: Pokemon that hear its ominous cry shake and return to their nests as fast as they can. // used for Houndoom in final
Houndoom: Parts of its skin are hardened and almost appear as if its bones have been flipped out.
Noctowl: same
Kingdra: Because it surrounds its body with ink it emits from the water in order to conceal itself, its appearance is hard to determine.
Phanpy: It can move its long upper jaw more freely than its limbs and it uses it to ward off enemies. // "Paon"; why this is called an upper jaw and not a trunk is absolutely beyond me
Donphan: same
Meganium: same
Porygon: same as final gold
Stantler: same
Smeargle: same
Tyrogue: same // "Gong"
HItmontop: same // it has eyes now instead of the horrifying pseudo-claydol in SW97
Smoochum: // Named Kisskiss! Differs from both SW97 and final!
Elekid: On days with poor weather, blueish-white electrical current flows in the gap between its horns.
Magby: same
Miltank: same
Blissey: same
Raikou: same // "Rai"
Entei: same // "En"
Suicune: very slightly different wording (みせる vs. final あらわした) but otherwise same // "Sui"; "Milky Way Pokemon"
Larvitar: Its soft body can absorb the shock from any attack and then relax. // It's actually supposed to look like a fucking mischevous blob lmao
Pupitar: Although it is in a pupal state, it can move unrestricted. It comes charging with its hard shell. // "charge" may literally be the move "Take Down"
Tyranitar: Its forehead is said to be the hardest thing on land. Charging with its forehead, there is nothing it cannot break. // Did you know? Tyranitar = Rampardos. same point on "charge" as above
Lugia: same
Ho-oh: same
Celebi: Nobody knows details about its rumored existence. Currently under thorough investigation.
Ledyba: same
Ledian: specifically mentions that it has 7 stars and is called "7 Star Pokemon". seems it went through a lot of different star numbers - 3 in SW, 7 here, 5 in final, go figure. Ledian == Marshadow?????
Spinarak: If suddenly attacked, it raises its back and shows the face pattern on it; while the enemy is surprised, it flees.
Ariados: It starts to eat after emitting a thread from its mouth and its rear and restraining its prey. // Named "Ariadne", which is different form both SW97 / final
Cyndaquil: same
Crobat: same
Quilava: The fur that covers its body does not burn in any fire. It is fine even in lava. // very similar
Yanma: same
Chinchou: same
Pichu: same
Cleffa: same
Typhlosion: same
Igglybuff: same
Togepi: same
Togetic: Flying floatily, it looks for a kind person that seems like they will grant it happiness.
Natu: same
Xatu: same
Totodile: Thrashes about more than one would imagine from its size. Teeth it loses from biting grow in one after the other. // same first sentence as final, same second sentence as first sentence of final Croconaw
Mareep: same
Croconaw: It spends most of its day with just its eyes and snout above the water's surface.
Flaafy: same
Ampharos: slightly different; "The bright light on its tail can be seen far away. It has been treasured since ancient times in place of a beacon."
Bellossom: same
Marill: same
Azumarill: same as final gold version
Feraligatr: same // "It is hard for it to support its own weight out of water, so it gets down on all fours. But it moves fast. " then why the fuck is it standing on two legs in every appearance???
Sudowoodo: same
Politoed: same
Hoppip: same
Skiploom: same
Jumpluff: same

before I sleep I don't want to do the whole of gold so I'll just do the ones I think are different

Gold

Espeon: It has developed extrasensory power. It appears that, using its whole body, it can even sense things one would not otherwise know.
Misdreavus: slightly different; final version mentions it is specifically a prank / trick whereas original does not
Unown: same
Wobbuffet: When it takes in the sun, it slowly splits, so it hides in dark caves.
Shuckle: Berries stored in its pot-like shell seem to eventually turn into alcohol. // so this is why they banned berry juice in lc
Dunsparce: When attacking prey, it hits it with its head, violently and very hard, in order to knock it unconscious. // how it feels to get paraflinched to death in gamefreak lore
Scizor: same
Forretress: It has layered tree bark and made a sturdy shell, but the shell is heavy and it practically cannot move.
Sneasel: Its long, crescent-shaped claws are usually hidden in its fingers.
Larvitar: same
Pupitar: same
Tyranitar: same
Celebi: same as above
Ledian: same
Ariados: same
Feraligatr: slightly different; final adds "into shreds"