Oricorio is usually used to
- Push for the win by KOing two or more Prizes worth of targets on your opponent's side of the field; remember that Oricorio can hit Benched targets and places damage counters based on all Pokémon in your opponent's discard pile, not just Night Marchers.
- Take a key KO or KO's, and in doing so, disrupting your opponent's setup. A typical example is taking out Joltik (PHF) so that Mew (FCO) cannot copy it, or multiple Night Marchers so that you just need a final, typical OHKO of the opponent's Active to win.
- Intimidate your opponent, so he or she settles for weaker attacks than usual.
Marshadow-GX needs at least one
Joltik and four other Night March Pokémon in your opponent's discard to OHKO
Darkrai-EX (either version) or
Darkrai-GX for a
Double Colorless Energy. Of course,
Marshadow-GX might have a
Fighting Fury Belt or the like, but then again, so might
Darkrai-EX. Now, this is not a difficult threshold for a competent Night March deck to meet, but notice something; they are scoring a OHKO against
Darkrai-EX with a 150 HP, two-Prize Pokémon. While not a highly probable OHKO, Dark Pulse just needs six [D] Energy in play to OHKO
Marshadow-GX. OHKO versus OHKO, both with two Prize Pokémon, and whoever started the process first wins.
Night March
hates that. The deck is meant to trade single-Prize attackers for OHKOs. You said that only nine Night March Pokémon were needed in the discard pile to accomplish this, but let us remember what all that entails.
Joltik on the field and attacking, if it is trying to OHKO a
Darkrai-EX. It also carries the risk that a player can get the original
Darkrai-EX up front to attack with Night Spear... while also sniping a Benched
Joltik.
Guzma or
Escape Rope can make sure a formerly Active
Joltik is heading to the Bench.
If
Pumpkaboo (PHF) or
Mew are attacking, they would actually need
10 Night Marcher Pokémon in the discard pile, to overcome Psychic Resistance when attacking into
Darkrai-EX.
Pumpkaboo also needs
Dimension Valley or a third Energy. Again, they
might have
Choice Band,
Fighting Fury Belt, or
Muscle Band equipped, but
Darkrai-EX might have
Fighting Fury Belt itself; I try to focus on the naked matchup, at least at first. One of the reasons I wish I had room for
Yveltal (XY) is because it can OHKO
Pumpkaboo for a single Energy
while accelerating Energy to something else. Nine Night March Pokémon in the discard pile is 75% of them; 10 is approximately 83%.
We'll now put it all together, working from my most recent bits. For Night March to attack with
Pumpkaboo, not only does it have the usual concerns, but it needs all but
two Night Marchers in the discard pile.
One of those must be itself, so there is no room for error,
and it becomes easy pickings for
Oricorio or
Yveltal.
Mew fares almost as poorly; while it lacks Darkness Weakness, it only has 50 HP and
requires another Night Marcher on the Bench, enabling double OHKO's and sometimes more!
Joltik continues the trend; while your opponent won't need another Night Marcher benched, with just 30 HP it feeds into more multi-KO's, still has to worry about
Yveltal, but also adds in a
Shaymin-EX Sky Return to remove a juicy target from the backfield of the Turb Darkrai player.
Marshadow-GX has to hit hard and fast
but with a moderate amount of Night Marchers in the discard pile, which stops working if
Yveltal or
Yveltal-EX are in the deck, or if the deck runs
Shadow Circle and can keep it in play, or if the deck runs
Karen.
Hex Maniac at the right time can leave the modern Night March unable to attack.
This is not to say that the matchup is in Turbo Darkrai's favor; having been on both sides of it, I'd say that
without the semi-specific counters to each other, it favors Night March, but not dramatically.
Hoopa-EX and/or
Shaymin-EX getting OHKO'd creates an opening Night March will almost certainly exploit. When Night march
does reach OHKO levels againts Turbo Darkrai, it only need to do so three times in most matches... less any early OHKO's against supporting stuff. We haven't even gotten into supplemental tricks, like
Tauros-GX with a
Fighting Fury Belt,
Marshadow-GX with a
Focus Sash, or the nasty
Marshadow-GX with a
Focus Sash and Tauros-GX in the discard pile. XP