With each new Pokemon release, we get our hands on tins containing exciting promo Pokemon. Sometimes they're existing Pokemon that tie in with the set with all new artwork. Sometimes they're brand new cards, and these tins are the only way to get them. Burning Shadows gives us the former with the Mysterious Powers Tins, showcasing three of the GX Pokemon in the set: Marshadow-GX, Ho-Oh-GX, and Necrozma-GX. While nowhere near as flashy as Gardevoir-GX or Golisopod-GX, these Pokemon each have their uses and, with a little support, can carve out their own niche in the metagame.

Necrozma-GX is one of the harder cards to evaluate in the set because it does so many things that it's difficult to narrow down where it's best supported. While its Prismatic Burst attack denotes a Psychic deck being the best home, most Psychic decks right now aren't set up to realistically put enough Psychic energy on Necrozma for it to do any real damage. These decks tend to focus on single energy attacks, such as Trashalanche, and opt for using Double Colorless Energy should they require a bigger attack. However, Metagross decks tend to splash a few Psychic Energy, so it stands to reason that you could fit in Necrozma since you can power it up with Metagross's Geotech System.

As well, other energy-heavy decks like Volcanion and Gardevoir-GX can make use of Necrozma's Black Ray GX attack, which deals 100 damage to each of the opponent's EX and GX Pokemon. When used in tandem with Tapu-Koko and other "area of effect" attacks, this can seriously rack up the prize cards with just one attack. 

Ho-Oh-GX is a bit more narrow in its applications, but it is incredibly powerful in the current Standard. Ho-Oh, like most Fire Pokemon, requires a lot of energy to get going, but thanks to Kiawe from Burning Shadows, we can power up a Pokemon with four energy right away at the cost of our turn, making it the best turn 1 out there for Fire decks. From there, Ho-Oh becomes a monstrous attacker, dealing 180 damage with Phoenix Burn, and in Volcanion decks which already have a ton of ways to switch out Pokemon, we can even mitigate the drawback on the attack. Ho-Oh can even snipe smaller Pokemon on the bench with Sacred Fire, and since it's a basic Pokemon, you can even use Volcanion's Steam Up to boost its power even further. With all that going for it, I have no doubts that Ho-Oh will be the face of Fire decks for quite some time.

Finally, Marshadow-GX is a bit more difficult to place. Having access to all of the attacks of your discarded basic Pokemon is cool, but since so much of Standard has shifted toward evolution decks, we just aren't seeing cheap and powerful attacks on basics like we used to. That's why I believe that Marshadow's real home is in Expanded in the dreaded Night March deck. 

Night March predicates on having a bunch of Pokemon with the Night March attack in your discard pile, and since Marshadow gains the attacks of the basic Pokemon in your discard pile, this archetype is already in Marshadow's wheelhouse. Furthermore, having additional attackers with the Night March attack means we can discard even more Pokemon to fuel the attack since we don't need to have one sitting on the table to attack. This gives us a maximum base damage of 240, just enough to one-hit KO bulky Pokemon like Gardevoir-GX! Lastly, it's worth mentioning that Marshadow's typing also allows it to do double damage against most Normal and Dark Pokemon, such as the namesake of the Turbo Darkrai deck, which received a serious upgrade with the printing of Darkrai-GX, so that's definitely a bonus.

I have high hopes that these three Pokemon will start seeing more play as the metagame opens up. There are homes for each of these cards in existing archetypes, and with the power level on display, I wouldn't be surprised if we see even more tech slots being taken up by Marshadow, Necrozma, and Ho-Oh. So if you want to experience Mysterious Powers firsthand, crack open some tins and have fun!