Honestly, I think if Flutters knew she deserved one she would submit to it, maybe even confess to an authority figure if she felt guilty enough. I mean, look how guilty she got in Putting Your Hoof Down.

5898845
Fluttershy knows she's weak and helpless.

And the face she makes says she wants you to show it to her.

5898845
Definitely - I can even see her badgering her parents into it/talking them through it. (Perhaps out of guilt, perhaps in the hope they might then apply this new trick to Zephyr when he earned it.) Of course given how the family turned out, I doubt she had much success.

6823775
I do think that since she's so delicate you do need to do it well.

6823826
She comes off as delicate because of her personality, but that doesn't necessarily translate into physical fragility. And while we've seen her frightened of many things, is pain one of them?

6823857
I also meant mentally. With Fluttershy I don't think excessive cruelty will really be the way the go. Rather a more gentle spanking with the scolding as primary punishment. I actually do think Fluttershy's tolerance for pain is quite high. She has a lot of self discipline as evident by her devotion to take care of her animals and she is very patient so she can easily tough something out.

6823863
Well, given her parent's personalities I think they'd only be spanking her at her own insistence, and even then reluctantly. So excessive cruelty is unlikely (and scolding fairly redundant).

6823892
With scolding I mean while the spanking is going on.