Say I'm using a Kingdra with scald (80 BP), would rain dance make the base power 160 (x2) because its in addition to stab or does it multiply with the already stab scald making it 180 (x2.25)?
STAB and rain would increase the power by 50% each. So 80x1.5=120x1.5=180. So the BP of scald would be 180.
Source: Knowledge