About a year ago, TCGP introduced the "Shining Revelry" minor expansion or Themed Booster Pack, which contains the first batch of Shiny Pokémon as separate cards and sets a precedent for future expansions in containing such variants. The new expansion introduced for this month follows up on that and contains cards of similar composition and theme, but this time retaining the "grand theme" thus far of the B Series cards of which it is a part, being Mega Evolution. That is then appropriately reflected in the title of the expansion.
"Mega Shine", as it is called, features the entry of several other Mega Evolution forms with some distinct appearances, two of which are Mega Charizard X and Mega Gengar, who are also prominently featured in the pack image. It too is very similar in appearance to the aforementioned "predecessor" pack, with shades of white and other accent colors. Meanwhile, the pack also features other Shiny Pokémon, one of which is the Mythical Pokémon Mew; it's even there as an "immersive" card, making it unique thus far among expansions.
With regard to composition, the expansion contains 64 Pokémon cards, 2 Item cards, 2 Supporter cards, and 1 Stadium card for 69 cards in total in the numbered section. The "predecessor" pack, which has 68 Pokémon and 4 Supporter cards (72 total) in its numbered section, can then be considered to be comparable in composition in this regard. As for the overnumbered section, the new pack has 48 cards in it compared to the old pack's 39, and thus its total exceeds the old pack by only a little bit yet still making it comparable.
The target for this pack is certainly the Shiny cards, but that remains a challenge, especially since now (and has been for some time) all Shiny cards are the sixth "bonus" card in a pack, which also means they won't appear in Wonder Pick as well. So, a lot of pack opening is still needed for any pack and in particular this pack, whose Shiny representations may be some of the most coveted. Otherwise, the rest of the Pokémon are rather "stopgap" in nature.
It's plainly obvious that Shiny Pokémon are here to stay in TCGP, so continuing to celebrate their appearance is something great to do. This new minor expansion or Themed Booster Pack does just that, and this time it's also with Mega Evolution, making further inroads with the "grand theme" along with the Shiny theme. Both of these have their own brilliant qualities, and now together, they make for a fascinating part of the current series of cards in this game.
One year ago: Looking Back at Cycling Roads
Two years ago: More on Outfit Grades in Café Remix
Three years ago: The Minuscule and Enormous Qualities of Pokémon Species
Four years ago: The Type Icons, A New Standard
Five years ago: Differing Amounts of Pokémon Knowledge
Six years ago: Pokémon Helmet Covers?
Seven years ago: Pokémon Go Community Day, 4/13/2019
Eight years ago: Go at Home
Nine years ago: Paint It, Picross