A lot of gold shop items are included, but most (all?) are only C.
Old trick or treat sets are approximately B or C, with some exceptions.
The recent Lisa's Rainbow is also good for picking up items, but most of them are B or C.
I'm guessing you can still participate fully with appropriate gold shop items, but these items will give significant boosts to certain styles.
As of approximately 8AM PST/11am EST October 31st, here's what I have:
AVANTGARDE
A
S
S+
S
S+
CUTE
A
S
S+
S
S+
FEARSOME
A
S
S+
S
S+
STREET
A
S
S+
S
S+
VINTAGE
A
S
S+
S
S+
