Ex Sandstorm
The card rarities for Ex Sandstorm are basically the same as for Ex Ruby & Sapphire, except that the set contains no Basic Energy cards and there is no “error” print run. The rarity table looks as follows:
Just like with Ex Ruby & Sapphire, the Pokémon-ex are more common than the holos, and the rares are more common than the uncommons.
The raw data for the holos, rares and Pokémon-ex is as follows (dashed lines denoting where transitions from H8 to H7, R10 to R9 and EX16 to EX15 would occur):
Despite the sample being larger than for Ex Ruby & Sapphire, no definitive conclusions can be drawn.
I did not look at the uncommons, but was able to reconstruct the commons sheet. It looks as follows:
† Psyduck, Duskull (Haunt), Mysterious Fossil, Marill, Growlithe, Root Fossil, Cyndaquil, Natu, Slakoth, Ekans, Lotad (Tackle), Sandshrew, Spearow, Aron, Trapinch, Shroomish, Cacnea (Poison Sting), Wailmer, Ralts, Cacnea (Poison Payback), Skitty, Pikachu, Wingull, Cyndaquil, Zigzagoon, Duskull (Surprise), Omanyte, Seedot (Tackle), Dunsparce, Lotad (Rain Dish), Claw Fossil, Growlithe, Onix, Mysterious Fossil, Sandshrew, Eevee, Marill, Shroomish, Natu, Root Fossil, Ekans, Seedot (Surprise Attack), Psyduck, Slakoth, Duskull (Surprise), Seedot (Tackle), Aron, Marill, Spearow, Psyduck, Dunsparce, Trapinch, Omanyte, Eevee, Lotad (Tackle), Wailmer, Cacnea (Poison Sting), Pikachu, Wingull, Duskull (Haunt), Skitty, Cacnea (Poison Payback), Natu, Zigzagoon, Lotad (Rain Dish), Shroomish, Ekans, Claw Fossil, Onix, Mysterious Fossil, Growlithe, Root Fossil, Sandshrew, Cyndaquil, Slakoth, Ralts, Pikachu, Spearow, Eevee, Trapinch, Seedot (Surprise Attack), Dunsparce, Wailmer, Onix, Wingull, Lotad (Tackle), Zigzagoon, Omanyte, Claw Fossil, Cacnea (Poison Payback), Mysterious Fossil, Marill, Seedot (Tackle), Ekans, Natu, Aron, Skitty, Duskull (Haunt), Cyndaquil, Shroomish, Psyduck, Growlithe, Root Fossil, Cacnea (Poison Sting), Slakoth, Ralts, Duskull (Surprise), Spearow, Sandshrew, Pikachu, Trapinch, Lotad (Rain Dish), Wailmer, Dunsparce, Wingull, Omanyte, Zigzagoon, Eevee, Seedot (Surprise Attack), Onix, Claw Fossil †
As with Skyridge, the commons chosen to appear once fewer on the sheet were Pokémon with two versions in the set.
As for the reverses, the sample yielded 16% reverse rare holos, 10% reverse rares, 34% reverse uncommons and 40% reverse commons. The RE2 cards may all be reverse commons (which would yield 13% reverse rare holos, 12% reverse rares, 30% reverse uncommons and 45% reverse commons), but given the size of the sample (252 packs) I would almost be inclined to say it is more likely that they are a mixture of reverse commons and uncommons.
Edit 23/04/16: edited text on reverses to reflect likelyhood RE2 cards are actually a mixture of reverse commons and reverse uncommons