Well, according to the English cards we have seen, the set will be at 132 cards. If they are taking out Darkrai, Darkrai Lv.X, Palkia Lv.X, and Dialga Lv.X from the Japanese set and replace them with Garchomp Lv.X, Gardevoir (can't have the Lv.X w/o it), Gardevoir Lv.X, and Honchkrow Lv.X, that will leave us at 117 cards (since IIRC the Japanese DP3 set has 117 cards according to the official Pokemon Card site ignoring the Energies). The following list is what I THINK would be the holo list for Secret Wonders after taking a look at the Japanese list and some of the US cards' numbers (Assuming that Gardevoir from DP4 will be included in this set)
1 Ampharos
2 Blastoise
3 Charizard
4 Entei
5 Flygon
6 Gallade
7 Gardevoir
8 Gastrodon (East)
9 Gastrodon (West)
10 Ho-oh
11 Jumpluff
12 Lickilicky
13 Ludicolo
14 Lugia
15 Mew
16 Raikou
17 Salamence
18 Suicune
19 Venusaur
Adding the Electivire, Weavile, Magmortar, and Roserade makes it 121. Now the question is what will happen to the other 11 cards? I am thinking that 4 MIGHT be new/reprint/etc. versions of Electabuzz, Sneasel, Magmar, and Roselia out of those 11 ... that probably leaves 7 unspecified cards. However, the Japanse set only has 3 Trainers in the set (Hamana's Research, Oak's Visit, and Mars) and in the English version Oak's Visit and Mars are numbered 122 and 126 respectively. So there might be some Trainers/Supporters/Stadiums will also appear in this set (that might be new, but I am betting most are reprints). Gee, I wish Saturday could come faster so all the mysteries will be unfolded.
EDIT: Took out the Rare list since I am stuck at something ...