It is a substyle in the fashion, but it is only appropriate for conventions where cosplaying an anime character who is a Lolita or for another kind of costume party. It is not generally acceptable to other Lolitas for street wear or for a Lolita meet-up. Or an Angelic Pretty Tea Party….

{paste from 2012 ACen Tea Party guidelines}
Cosplay is not permitted. Any and all cosplay ensembles are inappropriate. Examples include, but are not limited to:
• Purposefully replicating anime characters and their respective outfits
• Purposefully replicating brand-themed coordinates (such as those in advertising or print campaigns) in a cosplay-like style or manner
• Mana cosplay
• Chii ears, Naruto headbands, cosplay wigs, etc.
• Cosplay-related props and/or weapons

These are in addition to requiring Angelic Pretty and of course no replicas for the Tea Party, and men in formalwear but that is another story.

This photo is an example of me at a mainstream public costume party wearing a perfectly acceptable off-brand dress that I’ve worn to Lolita meet-ups, but here it is deliberately styled in as a costume, a ‘Clockwork Doll’ character.
Some differences:
Exaggerated doll-like styling and makeup
Deliberate ‘oldschool’ elements and a fairly strong Ita feeling is purposely evoked
Headdress streamers loose
Rosettes on each side of headdress
Oversized key accessory
Cheap repurposed fan
Lace mitts
Huge ring

Singly, a case could be made for any of these elements in a regular coordinate except the key.
Together they are a ‘costume!’…