IVs of 0 are read as 31 by correctHiddenPower

[ctl2]

This line doesn't differentiate between IV values of 0 and undefined

damage-calc/src/js/shared_controls.js

Line 963 in 81f2e78

var iv = ivs[legacyStatToStat(s)] = (pokemon.ivs && pokemon.ivs[s]) || 31;

This is an issue for any pre gen 7 set with hidden power in its moveset & 1 or more IVs of 0. The gen 5 Bronzong (OU Tank) set should have a speed IV of 0, but gets assigned 31 instead (which has a big effect on its gyro ball damage).

Can be fixed by changing the line's || to ??.

[ctl2]

also, nbd but I think the for loop's condition should be < rather than <=

damage-calc/src/js/shared_controls.js

Line 961 in 81f2e78

for (var i = 0; i <= LEGACY_STATS[9].length; i++) {