>>36807539Hidden Ability.
A rare, and sometimes ONLY transferred from pass gen(Gen 1 and 2 VC on 3ds are always 100% HA) of pokemon.
USUM HA able to be acquired. SOS chain a bit or get lucky outright. Yet lets take Ho-Oh or Lugia into account(or any legendary, they all need event or transfers from old VC shit) for HA.
Lugia/Ho-Oh and most older legendaries all have Pressure. Shit that makes PP usage double. Yet if I transfer lets say Lugia from Gold VC on my 3DS to USUM, it will 100% get its HA which is Multiscale. At full HP you take 50% damage of any attack. That is vastly superior to Pressure(on top of Lugia being one of the top stats and best tanks). Sadly, most of the best legendary HA are illegal(since the legendary are themselves), and almost no transferred from gen1/gen2 HA are competitive in a very serious manner(as in even coming close to VGC) but can be extremely fun and unique for casual ranked and things like battle tree.
Casual battles at like level 100 with some HA legendary are fucking broken and fun.