The Arba Minim (four species) are not taken on the Shabbat of Sukkot. As such, since they serve no practical purpose on Shabbat, they have the status of Muktzeh and may therefore not be moved.
This Halacha, however, applies only to the Lulav, the Hadasim and the Aravot. With regard to the Etrog, Chacham Ovadia Yosef rules (in Chazon Ovadia, Hilchot Sukkot, p. 375) that it is not considered Muktzeh on Shabbat, since it emits a pleasant fragrance and can therefore be used for smelling. The Shulchan Aruch rules that one should not smell an Etrog that was designated for the Mitzva of Arba Minim, but, as Chacham Ovadia notes, smelling an Etrog is allowed if one first takes to smell a different fruit or an Etrog that was not designated for the Mitzva and recites the Beracha over its fragrance. He may then smell even the Etrog earmarked for the Mitzva on the basis of the Beracha recited over the other fruit. Therefore, since there is a manner whereby the Etrog serves a practical purpose on Shabbat, it does not become Muktzeh, and one may move it on Shabbat and smell it in the manner described.
Are the Arba Minim considered Muktzeh on the night of Yom Tov, given that the Mitzva can only be fulfilled during the daytime hours?
Chacham Ovadia Yosef rules (in Chazon Ovadia, Hilchot Sukkot, p. 372) that the four species are not considered Muktzeh at all on Yom Tov, even at night. It is therefore permissible to tie one's Hadasim and Aravot to the Lulav on the night of Sukkot, provided that he makes a permissible knot, such as a slipknot or if he wraps the material around the Hadasim and Aravot and then tucks it under. And although the obligation takes effect only in the morning, one may nevertheless prepare the species for the Mitzva during the night, since the morning will inevitably arrive at which point the obligation will take effect. Chacham Ovadia compares the Mitzva of Arba Minim in this regard with the Mitzva of Tzitzit: just as one may tie Tzitzit to a garment at nighttime, despite the fact that the Mitzva does not apply at night, so may one prepare the Arba Minim on the night of Yom Tov, regardless of the fact that the Mitzva takes effect only the next morning.
Summary: One's Lulav, Hadasim and Aravot are considered Muktzeh and hence forbidden to be moved on Shabbat of Sukkot. The Etrog, however, may be moved on Shabbat of Sukkot. One may smell the Etrog during Sukkot, including Shabbat, if he first recites the Beracha over smelling some other fruit or an Etrog that was not designated for the Mitzva of Arba Minim. On the night of Yom Tov, the Arba Minim are not Muktzeh, and one may tie the Hadasim and Aravot to the Lulav at night, provided that he uses a slipknot or the "wrap and tuck" method of tying.
