Answer 1

In sinnoh the meteorites in veiltstone city trasform him into differant ones. in HGSS on the route that leads from vermillion to the power plant there are similar meteorites that work the same way

Comments

Actually, for HGSS, it is between Pewter City and Mt. Moon.

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Yeah, in Route 3.

Answer 2

If you go to Veilstone city there'll be 4 meteorites in the ground the
- top = is speed form
- middle = is normal form
- bottom left = defence form
- bottom right = attack form

Have deoxy in your party to check the stat changes when you touch the meteroites.