Naganadel is a Pokemon that has all the right things going for it; a great dual stab combination, excellent offensive stats, the ability Beast Boost, and exactly what it needs in its movepool.
The set that we believe breaks this Pokemon is the Nasty Plot + Dragonium Z set. With a moveset of Nasty Plot, Draco Meteor, Sludge Wave, and Fire Blast, Naganadel is practically unwallable outside of Heatran and AV Tyranitar, with very few other switch-ins. Devastating Drake is Naganadel’s nuke for netting easy KOs on non-resists and Sludge Wave beats Fairy types that can take its Dragon-type moves. Fire Blast is the perfect coverage move to defeat the remaining defensive stalwarts standing in the way of its STAB combination – Steel-types. Nasty Plot makes Naganadel a threatening breaker and an even more threatening sweeper in conjunction with Speed boosts from Beast Boost.
Here are some examples that show how devastating this Pokemon can be in action:
+4 252 SpA Naganadel Devastating Drake (195 BP) vs. 248 HP / 8 SpD Eviolite Chansey: 595-702 (84.6 - 99.8%) -- guaranteed 2HKO
+4 252 SpA Naganadel Devastating Drake (195 BP) vs. 248 HP / 220+ SpD Heatran: 332-391 (86.2 - 101.5%) -- 12.5% chance to OHKO
+2 252 SpA Naganadel Draco Meteor vs. 0 HP / 4 SpD Tyranitar in Sand: 279-328 (81.8 - 96.1%) -- guaranteed 2HKO
+2 252 SpA Naganadel Fire Blast vs. 252 HP / 132+ SpD Celesteela: 374-440 (93.9 - 110.5%) -- 62.5% chance to OHKO
+2 252 SpA Naganadel Devastating Drake (195 BP) vs. 252 HP / 252+ SpD Toxapex: 351-414 (115.4 - 136.1%) -- guaranteed OHKO
252 SpA Naganadel Devastating Drake (195 BP) vs. 252 HP / 24 SpD Landorus-Therian: 366-432 (95.8 - 113%) -- 75% chance to OHKO
252 SpA Naganadel Sludge Wave vs. 0 HP / 4 SpD Tapu Lele: 270-320 (96 - 113.8%) -- 81.3% chance to OHKO
252 SpA Naganadel Fire Blast vs. 252 HP / 168 SpD Ferrothorn: 360-428 (102.2 - 121.5%) -- guaranteed OHKO
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As you can see, Naganadel was kind of a menace in OU, with base 127 special attack and 121 speed, add a Nasty Plot in there and you start to OHKO nearly everything.
With Life Orb, STAB, and one Nasty Plot, Devastating Drake becomes a 380.5 base power nuke that just obliterates everything that doesn't resist it, (which is only steel and fairy.) Add Sludge Wave and Fire Blast to counter those two types, and you get banned to Ubers.
But, just because a Pokemon is banned to Ubers doesn't mean that it is viable there. To quote a previous answer of mine:
Naganadel on the other hand struggles immensely to be of any use. It is the inferior Poison-Dragon type to Eternatus in Ubers. Because of its weak defenses, it is easily countered by threats such as Groudon and Excadrill. Even with a speed boost, it is outsped by Choice Scarf Calyrex-S, who can OHKO it. Naganadel relies on Nasty Plot to be exceptional, which allows it to be KOed while it's setting up.
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So Naganadel falls into competitive obscurity, banned to Ubers however being completely unfit to battle there.
Hope I helped!
