Sorry to burst your bubble but no. there is no way that ampharos can learn ice punch in generation four or three, there is no point in stating lesser generation due to the lack of transfer ability. this is also despite the fact that ampharos can learn thunder and fire punch. to make matters even worse for this Pokemon, he cant learn any damaging grass or water type moves to counter ground type moves.
This may be a bummer, but the most likely reason why it cannot learn ice punch or moves that can counter ground types in general is because he would be to o.p.
due to pure electric typing, his only weakness would be ground, ground types are generally slow Pokemon, except for Dugtrio, and the electric ampharos has meh base 55 speed allowing it to get outsped and possibly be destroyed by an earthquake.
update, I have gen 3 emerald versions and I know there is a tutor with ice punch as well as one in or as, ill check if it is possible to teach it ice punch, but dont hold your breath
But if you really commited for an ice type move, you can always breed an ampharos for hidden power, which type and power depend on the Pokemon itself. this also means that you can breed a good nature, (tip, when you get the desired nature for your Pokemon but not the right hidden power, give the good natured ampharos an everstone and breed with it, increases the childs chance of having the same nature).
ps, now that the new mareep is just hatched, you can evolve it and ev train it as well, making it a killing machine.
