There's always the Gamefaq boards

In any case I have:

#85 Dodrio (evolve)
#90 Shellder
#115 Kangaskhan
#120 Staryu
#128 Tauros

#152 Chikorita
#155 Cyndaquil
#156 Quilava
#157 Typhlosion
#158 Totodile
#161 Sentret
#162 Furret
#169 Crobat
#171 Lanturn
#176 Togetic
#177 Natu
#181 Ampharos
#186 Politoed
#192 Yanma
#193 Yanma
#198 Murkrow
#200 Misdreavus
#204 Pineco
#210 Granbull
#211 Qwilfish
#214 Heracross
#216 Teddiursa
#217 Ursaring
#220 Swinub
#222 Corsola
#226 Mantine
#228 Houndoor
#241 Miltank
#251 Celebi

#274 Nuzleaf
#286 Breloom
#285 Shroomish (SS)
#290 Nincada
#300 Skitty
#301 Delcatty
#303 Mawile
#310 Manectric
#320 Wailmer
#326 Grumpig
#330 Flygon
#335 Zangoose
#336 Seviper
#341 Corphish
#348 Armaldo (evolve)
#357 Tropius
#368 Gorebyss
#374 Beldum
#380 Latias (SS)
#381 Latios (SS)

#409 Rampardos
#415 Combee
#416 Vespiquen
#421 Cherrim
#429 Mismagius
#430 Honchcrow
#443 Gible
#444 Gabite
#445 Garchomp
#446 Munchlax
#463 Lickilicky
#473 Mamoswine
#474 Porygon-Z
#479 Rotom

#491 Darkrai
#492 Shaymin

And these are just off the top of my head, I could have more but I'm too lazy to check.
Most of these I can trade you, but some would have to be trade and trade back if you just want dex completion.