The Hoshana Rabbah greetings:

Some are accustomed to greeting each other with Gut Yom Tov on Hoshana Rabbah.[1] Likewise, on Hoshana Rabbah, some are accustomed to greeting each other with the blessing of Piska Tava, or a Gutten Kevittle, Gemar Chasima Tova. The Chabad custom, however, is not to greet one’s friend with such greetings.[2] [Nonetheless, the Rebbe was accustomed to wish the Jewish people, in  his public talks, with a Gutten Kevitel.[3]]

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[1] See Aruch Hashulchan 664:13

[2] Sefer Haminhagim [p. 146 English edition] from the Friediker Rebbe [Sefer Hasichos 1948 Sichas Hoshanah Raba] that we do not say Gmar Chasima Tovah or Piska Tova on Hoshana Rabba.

[3] Hisvadyus 5746 1:309; 5751 1:163