The Draco Plate might be the most useful one, because Dragon moves have the best neutral coverage -> are spammable. You might not miss some important KOs - and it let you live longer in almost omnipresent sandstorm. The most important thing is Fire moves easily cover almost all resistances and rarely needs a Life Orb boost.
MixMence (Naive, 252 SAtk) and Hydreigon (Timid, 252 SAtk) might get into trouble without Life Orb, because they can miss a 2HKO on Ferrothorn (Impish, 252 SDef) with Fire Blast in rain, as it only does 168 - 200 damage and 184 - 220, including Leftover Mence almost never 2HKO. The Life Orb ones do 220 - 260 (62.5% - 73.9%) or 240 - 284 (68.2% - 80.7%).
Note: Modest Hydreigon always 2HKO Ferrothron in rain and therefore don't need a Life Orb.