Here you go. A list of Platinum-only Pokemon. (i.e., not in HGSS)
Turtwig
Grotle
Torterra
Chimchar
Monferno
Infernape
Piplup
Prinplup
Empoleon
Starly
Staravia
Staraptor
Bidoof
Bibarel
Kricketot
Kricketune
Shinx
Luxio
Luxray
Budew
Roselia
Roserade
Cranidos
Rampardos
Shieldon
Bastiodon
Burmy
Burmy
Burmy
Wormadam
Wormadam
Wormadam
Mothim
Wurmple
Silcoon
Beautifly
Cascoon
Dustox
0
Pokémon
Combee
Vespiquen
Pachirisu
Buizel
Floatzel
Cherubi
Cherrim
Shellos
Shellos
Gastrodon
Gastrodon
Drifloon
Drifblim
Buneary
Lopunny
Mismagius
Honchkrow
Glameow
Purugly
Barboach
Whiscash
Chingling
Chimecho
Stunky
Skuntank
Meditite
Medicham
Bronzor
Bronzong
Bonsly
Mime Jr.
Happiny
Pokémon
Chatot
Spiritomb
Gible
Gabite
Garchomp
Munchlax
Riolu
Lucario
Wingull
Pelipper
Hippopotas
Hippowdon
Azurill
Skorupi
Drapion
Croagunk
Toxicroak
Carnivine
Finneon
Lumineon
Feebas
Milotic
Mantyke
Snover
Abomasnow
Weavile
Uxie
Mesprit
Azelf
Dialga
Palkia
Manaphy
0
0
Pokémon
Rotom
Gliscor
Nosepass
Probopass
Ralts
Kirlia
Gardevoir
Gallade
Leafeon
Glaceon
Swablu
Altaria
Togekiss
Magnezone
Tropius
Rhyperior
Duskull
Dusclops
Dusknoir
Porygon-Z
Electivire
Magmortar
Snorunt
Glalie
Froslass
Absol
Giratina
I did this all on Excel, so excuse the random zeros and the empty spaces.
The spaces are other Pokemon that appear in HGSS.
Also, there might be a few repeats of a Pokemon's name - the source said different forms as well, which bugged me. .-. 'Xcuse them as well.
Furthermore, excuse the random occurrences of the word 'Pokémon'. They normally appear where a random zero is.
Hope I helped. :)
Source, Myself, and the magical wonders of Microsoft Excel.
