According to the Sefardim, why is the Brocho on Matzo Hamotzi on Pesach, if it's Mezonos the entire year? What changes?
(for why mezonos a whole year see here)
Most Sephardim use "soft" matzah instead of "hard" matzah, and "soft" matza technically has the brakha of HaMotzi. "Hard" matza is more a problem, though there are many Sephardim, especially Chutz L'Aretz, that use it. Essentially according to Sephardi Halakha hard Matza is not mezzunot, it is sofek mezzunont/sofek lehem. Most Sephardi poskim hold that the Chiuv of the day overrules the sofek. There have been some extensive teshuvot written about this in the last hundred years since hard matza was introduced to Sephardim. Yehave Da'at 1:91 and 3:12 Yaskil Avdei 6:18, 8:5, and 8:52 are a couple of places that it is dealt with at greater length.
It is an undisputed fact that Hazal only gave the Beracha of Hamotzi to products of the five grains that are normally used as a meal. If the product is normally used for snacking then the beracha is mezonos unless one eats enough of it for it to anyway be considered a meal. There is a type of bread called "Pas Habaah bikisanin" that is not usually eaten for a meal. There is a 3-way dispute as to the definition of this type of bread. One opinion is that its consistency is not that of bread, rather it is hard and brittle. Since there are 2 other opinions on the definition that would disagree with the beracha of hard brittle bread being mezonos, it is a safek to us what its beracha is (as well as a safek if one must wash for it).
To disagree with the other responses, many sefardim use the hard matzot for Pesach, especially in Hutz La'Aretz. They still make HaMotzi on it on Pesach because on Pesach it is normal to use such cracker-matzoh for a meal. Once Pesach is over and regular bread is permissible, it becomes unusual to use hard matzoh as a meal and therefore its beracha becomes a mezonot.