Gen 8 VGC (doubles), with Trick Room support
Regidrago @ Iron Ball
Ability: Dragon's Maw
EVs: 252 Atk / 128 Def / 128 SpD
IVs: 0 Spe
Brave Nature (+Atk/-Spe)
- Dragon Claw
- Hammer Arm
- Fire Fang
- Protect
This is a physically offensive build for doubles with Trick Room support. It appreciates screens.
Iron Ball is necessary to fix Regidrago's middling speed tier within Trick Room. It cannot be removed in favor of setting up with Hammer Arm, since Iron Ball reduces speed by a half whereas Hammer Arm reduces speed by only a third. Moreover, Iron Ball requires no setup, whereas Hammer Arm requires one or more setup turns before it can confer a speed advantage, during which time Regidrago can be KO'd due to its abysmal base defenses.
Def and SpD are given EVs instead of HP since Regidrago's base HP is already sky-high whereas its base Def and SpD are abysmal. Besides, this build does not include any moves that are HP-sensitive (e.g. Dragon Energy, Reversal, Substitute), and so overall survivability is prioritized over HP maximization. The EVs remaining after maximizing Atk are split evenly between Def and SpD because this is a doubles build, and so you are liable to face a mixed set of opponents at the same time. If you have more specific information to the contrary for your league/series, feel free to refine this distribution!
Dragon Claw is the primary move of this set. It gains both STAB as well as the boost from Dragon's Maw. It is chosen instead of the more powerful Outrage not only because Outrage confuses its user after 2-3 turns, but more importantly because this is a doubles build. In doubles, Outrage randomly selects its target from among your opponents; it is rare that both opponents are weak to Dragon; it is common that at least one opponent resists Dragon; and it is eminently possible that one opponent is entirely immune to Dragon. Similarly, this expected type distribution of your opponents is the same reason why the spread move Breaking Swipe is not considered even though this is a doubles build. (Also, Breaking Swipe's side effect of lowering the targets' Attack is not useful enough to justify it since there is a good alternative in the ability Intimidate, and since the most common attacks among the types that Regidrago is weak to are all special: Draco Meteor, Ice Beam, Moonblast/Dazzling Gleam.)
Hammer Arm is a coverage move that is unusually strong (100 Power). Its main benefit is that it is super effective against Steel types that would otherwise resist Dragon attacks. It also decreases the user's speed, which would normally render Hammer Arm unviable for a Pokémon with as poor defenses as Regidrago, but is instead beneficial within Trick Room. However, as explained above, the self-slow from Hammer Arm does not obviate the need for Regidrago to hold an Iron Ball; rather, Hammer Arm's side effect should be considered as only a supplementary source of speed reduction. Finally, if you are in Gen 8, Hammer Arm does manifest during dynamax as Max Knuckle, which confers the benefit of boosting physical Attack (which this Regidrago build actually uses).
Fire Fang is another coverage move. Its main benefit is also that it is super effective against Steel types that would otherwise resist Dragon attacks. Secondarily, it is unresisted by all the types that resist (or are immune to) Fighting. Thus, the combination of Hammer Arm and Fire Fang provides unresisted coverage against all Steel dual types. Moreover, this Regidrago's combination of the attack types Dragon, Fighting, and Fire is super effective against more Pokémon and resisted by fewer Pokémon than if either Hammer Arm or Fire Fang were swapped out for the next most popular physical coverage move: Crunch.
Protect is included because this is a doubles build. Its main benefit is that it shields Regidrago (who has poor defenses) while your doubles ally sets/resets Trick Room. Its secondary benefit is that it can be used in the face of a lethal threat to buy Regidrago a turn, during which time your doubles ally can eliminate the threat (or at least weaken it enough for Regidrago to KO it the following turn).
