Ex Team Magma vs Team Aqua
When looking at this set, I noticed I had made a mistake with the reverses: The RE2 cards are in fact not all reverse uncommons, there is one reverse rare (Double Rainbow Energy) printed twice on the sheet. This led me to update the text of some of the older posts above. My general working hypothesis for the future will still be that the “extra” spaces on the reverse sheets are filled in one rarity at a time, unless there is evidence to the contrary.
Beginning with this set, holos and Pokémon-ex started appearing in the rare slot again instead of in the last commons slot, as had been the case since Expedition. Also, Pokémon-ex became rarer, and holos more common. Thus, a box generally contains 24 non-holo rares, 9 holos and 3 Pokémon-ex.
The set contains two secret rares. One (Absol) is a box topper (not obtainable in packs and thus designated “O” for “other” in the rarity table). As to the other, Jirachi, the (very small) sample of 3 booster boxes opened on Youtube yielded 2 Jirachi (both from the same box). The upshot of the discussion on the PokéGym forums (The So called secret rare | The PokeGym) isn’t really conclusive, but I will assume Jirachi has the same rarity as the other holos and is a H8 card. To quote the forums, its “secret rare, not super rare”. (Spoiler for the future: the next secret rare holo, Here Comes Team Rocket! from Ex Team Rocket Returns, isn’t just secret rare, it is also super rare.)
The rarity table looks as follows:
As can be seen, the Pokémon-ex are now rarer than the holos, and the rares aren’t as common than in the first three ex-Series sets, but they are still more common than some of the uncommons.
The raw data for the holos, rares and Pokémon-ex is shown below (dashed lines indicating where transitions from H9 to H8, R11 to R10 and EX16 to EX15 would occur), but just as for the previous set (Ex Dragon), the sample is too small to draw any conclusions.
I didn’t investigate the commons or uncommons.
As to the reverses, the sample yielded 9% reverse rare holos, 10% reverse rares, 51% reverse uncommons and 30% reverse commons, which is in very good agreement with the Italian reverses sheet of which various images can be found online (Reddit - Dive into anything, but also other pages showing the part of the sheet not visible on this image). Thus, I am assuming the English sheet is the same as the Italian one, with 21 of the 22 RE2 cards being reverse uncommons, and one (Double Rainbow Energy) being a reverse rare.