Your impact testing requirements are not related to the material, its related to service requirements.
For example, SA-333 Gr 6 material is quite common in piping systems. This material is automatically, by specification, tested at -50degF for impact toughness. However, this does not kick in the requirement that a weld metal or WPS be requalified to -50.
However, the language in some of the codes ties it through the base material (for example, if the base material requires impact testing the weld metal requires impact testing, and sometimes the HAZ) but it is still ultimately related to the requirements of the service design. In other words, if the service design requires impacts on the base metal it may require impacts on the weld metal.