Darth Pika, I don't think 100% of the decks in top cut were SPs. Not even close.
1 Thomas A- Gengar/Luxray
2 Aylam R- Mother Gengar
3 Jason C- Gechamp
4 Alex M- Aperay
5 Grafton R- Flygon/Weavile
6 Aaron H- GGvile
7 Michael Z- Mother Gengar
8 Kevin C- AMU
9 Nathaniel L-Flygon
10 Ankur P- Dialga G
11 Jacob T- Dialga G
12 Jason A- Mother Gengar
13 Alexander B- GG w/ Gengar
14 Aziz A- Flygon/Weavile
15 Michael B- GG
16 kevin a- Palkia Lock
17 Samuel L- Mother Gengar
18 Kennan M- Beedrill
19 Jonathan B- Gengar
20 Austin Z- Aperay
21 Eric W- Gechamp
22 Robert C- Beedrill
23 Alec N- Mother Gengar
24 Eleki R- Gallade 4
25 Michael D- Gechamp
26 James H- Mother Gengar
27 Quinn D- Regigigas
28 Lloyd W- Dialga/Gallade/Honchkrow
29 Jarret A- Mother Gengar
30 Spencer B- Mother Gengar
31 Geoffrey S- Aperay
32 Christian H- Aperay
That's 10 SP decks.
10/32= 31%
All in all, SP decks tend to be great in the early game, but seem to run out of steam later (Legos can't seem to get enough energy attached between Dialga and Palkia and once Luxape runs out of Energy Gain it also seems to start to run low on energy from Infernape's discarding. Stage 2 decks don't run out of steam, but they tend to be less flexible and a bit slower in setup (setting up 3 energy on a Flygon, getting 4 Beedrill out, getting Gengar and Nidoqueen out, etc.) There really isn't a better choice.