I really hope I’m following all the rules on this question, please let me know if I’m not.
Anyway, I‘m curious about this because I had the idea that an Onix@Eviolite with an Impish nature with a 4HP/252DEF/252SPD EV spread using Body Press would deal incredible amounts of damage despite being a non-STAB attack. Onix’s base Defense stat is 160. With Eviolite it essentially becomes 240 (I think). Would Body Press calculate off that boosted stat? How much damage would that do? Smogon’s damage calculator uses the Attack stat instead of the Defense stat for Body Press calculations, last I checked.