Ex FireRed & LeafGreen
For Ex FireRed & LeafGreen, the number of Pokémon-ex per box increases from 3 to 4, of which one is a secret rare (one of the three legendary birds cards with a cracked-ice holofoil pattern), and the number of holos is reduced to 8. This is due to the fact that the set includes more Pokémon-ex than earlier sets - 12 in total including secret rares. The rarity table looks as follows:
“O” denotes the box topper, Charmander.
The raw data for the holos, rares, Pokémon-ex and secret rares is as follows, the dashed lines indicating where the transitions from H7 to H6, R9 to R8, EX13 to EX12 and SR37 to SR36 would occur:
No definite conclusion can be drawn from the data.
I did not look at the commons and uncommons.
As to the reverses, the data alligns pretty well with a 10x10 sheet being used, with 7 reverse commons being printed on the sheet twice:
Edit 23/04/22: typo in rarity table fixed (RE2 cards are likey reverse commons, not reverse uncommons)