learning moves?

[gamer22]

how to teach gengar ice punch and
how to teach aerodactyl ice fang?

[LoStic]

Platinum Move tutors -=- Pokemon Platinum

[gamer22]

how to learn it on diamond

[The Mole]

Here is a wonderful link the incredibly helpful Pokedex from Serebii.net

Going through it and checking the Pokemon will tell you what moves a Pokemon can learn, what level it is learned, whether it is egg bred or if it is a move tutor (namely the platinum stuff). As you will see on some pokemon though, they have moves listed that have a - instead of a level. This means it has to be relearnt by use of the heart scale person located in Pastoria City.

To answer you question though, before this is locked:

Aerodactyl learn Ice Fang through the use of heart scale in Pastoria City.
Gengar Learns Ice Punch through Egg Breeding & Platinum Move Tutor.

To get Platinum move tutor Pokemon in Diamond or Pearl, find someone who owns Platinum and ask them if they will tutor it on to him. Obviously then you trade to his Platinum and then he will trade back to your pearl once the move has been learnt.

I hope that has answered your question