>>33667143>Able to use Surf - Natu/Xatu/SmeargleYou can technically get Surf at Ecruteak City before going to the Burned Tower, Route 38, or Route 42. It lets you go through the surfing sections in Union Cave to the hidden area in the Ruins of Alph.
>Obtain Dragon Scale(s) - KingdraHorsea and Seadra can be obtained in the Whirl Islands (requires Whirlpool which you can use after beating Pryce), and have a chance of holding a Dragon Scale.
>Obtain Rainbow Wing - Ho-OhThe Rainbow Wing is obtained after stopping Team Rocket at the Radio Tower in Gold, but is obtained in Pewter City in Silver. Probably should have put this before Kingdra since it requires no HMs.
>Obtain Whirlpool and Silver Wing - LugiaThe Silver Wing is obtained after stopping Team Rocket at the Radio Tower in Silver, but is obtained in Pewter City in Gold. Requires Whirlpool and thus beating Pryce.
>Fisher Wilton swarm call - Remoraid/OctilleryIdentical to Fisher Ralph and Qwilfish, but on Route 44.
>Breed Jynx - SmoochumJynx is found in the Ice Path.
>Able to use Waterfall - Tyrogue/HitmontopPossible to do before Route 45, and it lets you access the rest of Mt. Mortar.
>Evolve Porygon - Porygon2The Up-Grade is found at Silph Co. You'll go to Saffron City before you go to Celadon City to get a Porygon from the Game Corner.
>Breed Electabuzz - ElekidElectabuzz is found on Route 10.
>Evolve Chansey - BlisseyChansey is found on Route 13.
>Breed Pikachu - PichuPikachu is found on Route 2.
>Breed Clefairy - CleffaClefairy is found in Mt. Moon.
Oh yeah, and
>Onix is available as early as Violet City through the Bellsprout trade, but can be found naturally in Union Cave, while Scyther can be found in the Bug-catching Contest at National Park.>Celebi has no natural location in Gold and Silver and can only be obtained through distributions.But if you ever wanted to know when your favorite Johto bro became available, that's the list for you.