First attempt at Concept Subs, Woohoo!
Name: Wait! It's a Trap Move!
Description: A Pokémon that can make effective use of semi-trapping, fully trapping, or self-trapping move(s).
Justification: Trapping is a somewhat polarized mechanic in the current SM metagame. In terms of ability-based trappers we have Dugtrio, perhaps one of the most hated (or most loved, really depends on the situation) Pokémon thanks to its ability Arena Trap. There is also the occasionally seen Magnezone that uses Magnet Pull to lure in and decimate Steel type Pokemon. All trapping effects are ignored by the Shed Shell item or simply by being a Ghost type. However, this is not the kind of trapping I want to focus on. Focusing on abilities leaves few options, and the general mechanics are the same: Lure, Trap, Destroy. Nothing much new is to be found there.
So, instead, I would like this concept to focus on trapping moves. For those unfamiliar with the term, there are a few types of trapping moves which I will make an attempt to explain here. A semi- or partially trapping move prevents the opponent from switching out for a set number of turns while also usually doing a set percent of damage. Example moves would be Whirlpool, Fire Spin, Infestation, and Magma Storm (but don't use that last one, it's legendary exclusive!). There are also what I like to call fully trapping moves, moves that prevent the opponent from switching not for a set number of turns, but instead until the Pokémon who used the move leaves the battlefield. This category includes moves such as Block as well as the brand-new Gen 7 moves of Anchor Shot and Spirit Shackle. Also are what I call self-trapping moves, which is just Ingrain to my knowledge. This move (and if any similar ones come about) lock the USER into battle. Lastly, just to make sure I cover all my bases, Fairy Lock is an interesting trapping move that prevents any Pokémon, friend or foe, from leaving the battlefield on the following turn only (Barring the usual exceptions).
This concept fits in the Actualization and Archetype categories. Trapping moves are exceedingly rare in their usage. The most effective in OU currently is Magma Storm Heatran, but this is by far not its only nor its best set. Expanding our gaze slightly we may find the strange Stall-Trap or Perish-Trap strategies in use in varying parts of the ladder. Even further? Ok then, in Ubers you can find an excellent example of self-trapping in Ingrain Xerneas, which helps prevent the opponent from forcing Xerneas out after it has set up its boosts. In addition, one could look at SD Trapper Decidueye that sets up with Swords Dance after trapping a helpless opponent via Spirit Shackle. Dhelmise can also use Anchor Shot, though I'm not terribly sure as to how that set works... Regardless, that makes about four solid examples of trapping moves across four different tiers, and none of the sets are by any means the only or most effective sets those Pokémon can run (Except maybe Dhelmise. Is there an RU player here who can help me out with that thing?). Overall, the relative rarity of these moves in competitive play when contrasted with the seemingly powerful effect of locking in the opponent begs a variety of questions about the nature and use of said trapping moves. To best explore these moves, designing a Pokémon to use and abuse them makes the most sense for understanding how to properly use them (whatever that would mean).
Questions To Be Answered:
(Base) Is there a 'best' way to utilize trapping moves? If so, what playstyle does it most align with?
(Base) Is there a 'best' type of trapping move overall, or are they each truly viable in their own ways?
(Base) What is the value in trapping the opposing Pokémon? Are certain traps better than others? Why?
(Base) What synergies work well with trapping moves? Why do they have such a great synergy, and how can that be expanded or dealt with in the process of teambuilding?
(Comparison) How do trapping moves compare against trapping abilities? Are there any inherent benefits and disadvantages and if so, what are they?
(Metagame) Are there any particular archetype matchups in which a trapping-move Pokémon would have an advantage? A disadvantage? Why is that?
(Metagame) What has contributed to the lack of presence of trapping moves in our metagame? Is it a plethora of other options, a lack of viable abusers, or something else?
(Metagame) How does the trapping mechanic interact with the value of switching out?
Explanation:
With the variety of different trapping moves available for use, a variety of archetypes can be built depending on the choice of move. To start, let's first analyze the semi-trapping moves. As mentioned before the basic applications for these fall in the categories of trapping and stalling out opponents through the use of Toxic or other status ailments. Alternatively, as with Heatran, it's used to trap vulnerable Pokémon in order to further weaken them to critical levels or straight up KO them. It was also mentioned during updates another strategy of using the moves of Pokémon who cannot do anything to your Pokémon and then setting up to sweep, as with Infestation on Aurumoth and Syclant, though this was generically deemed unviable. As for the fully-trapping moves, they are far more inclined to be used in the set up manner, as with the previously mentioned Decidueye. Again, stall sets works well with these moves as well, as they fully prevent escape instead of trapping just for a few turns. However, they do not do damage at the end of each turn, making the chip damage not as substantial. Ingrain honestly in the CAP metagame does not have any real foreseeable use. The anti-phasing properties applied to the Pokémon aren't useful unless you're trying to set up, and HazeHawk already makes easy work of any physical and non-SE moves if it switches in early enough. From there, it can usually chip you down. There could be some viability if you wanted to use super effective STAB moves such as Psychic type or Fairy type moves, but that seems a bit limiting, so I wouldn't necessarily encourage it unless someone thinks of a radically different use. Lastly we come to the more support-oriented role of Fairy Lock. The main way I have personally used this is on a Spikes, Dual Screens Lead Klefki. I let it set up until it was about to die, then used Fairy Lock to trap the opponent for an easy revenge kill. There are ways to use this move as more of a offensive role, by trapping at key points when you predict the opponent, but more importantly, this move is not very compatible with the stall playstyle, as the effect only lasts one turn. In addition to all of this, "trapping synergies with three great follow-up strategies: setting up, safely pivoting out, and using a powerful Z move lure" (snek), all of which can be considered when constructing the CAP. Overall, there are some similar threads of playstyles and archetypes, but each with its own niche.