Topic: Technique Research
Author: Kai Amarin
In my research into the vampirism condition Vo is afflicted with, I came to realize that no currently League-sanctioned technique implements Obscura or Spectral energy for the purposes of a draining attack. All things considered, this is understandable -- the one major historically-documented example of an Obscura-based draining move is none other than Yveltal's own Oblivion Wing. (Amusingly, in all documented cases where it was not used to lethality, it seemed to operate under the Flying-type's effectiveness rather than Dark like one would expect.) However, even including the League's ban on non-Legendary Pokemon using Oblivion Wing, it still stands that there is no acknowledgement of any sort of a Spectral-based technique.
Looking into it, however, there is a somewhat nonstandard technique that has been documented, with a few proposed "standardized" forms. The most commonly proposed is a form referred to as "Soul Bite", a Ghost-type attack modeled after Draining Kiss, which uses Spectral abilities to attach to and leech off of one's life force directly. Referring to the standardized form of Dream Eater as the upper limit of a given draining move's power (100%), limiting Soul Bite to approximately 50% of max power has been seen to give far superior efficiency in retaining drained energy, averaging around a three-fourths retention rate at that power level and lower (again, like Draining Kiss). This, of course, varies from species to species, and depending on the rate that the draining power decays, it is possible that there are more effective power levels; I have not had an opportunity to develop any sort of data set, due to personal moral restrictions on wanton use of life-draining abilities.
I have, however, had the opportunity to work with a number of Pokemon in tutoring the move. Working with Noland of the Hoenn Battle Factory has given me many opportunities to work with species beyond my own team, and as a Frontier Brain myself, this extends to interactions outside of battle as well. I have made a noncomprehensive list of confirmed, theoretically viable, and unlikely candidates for the ability, based on officially-sanctioned abilities as well as acknowledgement of similar lifeforce-feeding traits in the Pokedex.
Species that are absolutely, unquestionably capable of using the move include (in National Pokedex order): [Zubat-line], [Gastly-line], [Misdreavus-line], [Shuppet-line], [Dusclops and Dusknoir], [Froslass], [Cofagrigus], [Foongus-line], [Frillish-line], [Litwick-line], [Honedge-line], [Sandygast-line], [Morelull-line], [Mimikyu], and [Dhelmise]. Most of these are ghosts that are specifically cited in the standard-issue Pokedex to feed on souls, and thus were my first priority to work with. Using similar logic, it stands to be highly likely that the [Drifloon-line], as well as [Shedinja] (despite draining abilities being functionally useless to the species) are able to learn it without significant struggle. Ghosts without specific reference to soul-eating, but with known natural access to draining moves, include [Spiritomb] and the [Phantump-line]. Additionally, it stands incredibly likely that [Giratina], [Darkrai], [Lunala], [Yveltal], and [Marshadow] all probably have the ability to use it, due to legendary status (and my personal experience of seeing Giratina feast on a very unlucky megalomaniacal Gengar a few years prior to this study).
There are several ghosts, however, that do not have much indication for the capacity to learn the move. Most of the remaining known Ghost-type species can learn Dream Eater via TM or Drain Punch via tutoring, but despite this, Myra the Rotom has confirmed she can't figure it out, and Onabarrak the Golett is adamant about not attempting it. If they are capable of learning it, it certainly will prove much more difficult than usual. The one example of a Ghost-type species that is almost certainly incapable of utilizing it is Oricorio, who only have the Ghost-type as one of four forms anyway; Diane Jaide of the Pokedex Extended Fileshare Endeavor has done research on the species, and she is fairly confident in her assessment of the abilities they can learn.
In my list above, I cited a few non-Ghost-types that have successfully learned the move. These species are known for utilizing Spectral energy as well as having significant draining abilities, and therefore found it relatively easy to redirect the focus of the drain via Spectral energy manipulation in order to target the soul. Additional candidates include [Jynx], [Spinarak-line], [Lotad-line], [Cacnea-line], [Lileep-line], [Munna-line], [Klefki], and possibly [Tapu Lele] as well. For the most part, they have access to low-level Ghost-type moves such as Astonish, so in many cases it may take significant work to teach, but it is certainly feasible.
This has been a somewhat taxing study on my own energy, unfortunately, so I will likely put further research of this technique on the backburner.