Do Catholics believe in other apparitions like Mary? Or is she unique in that aspect
Mary is unique as only Mary possessed a real "glorified body & soul".
The Catholic Church had not approved nor attributed any claimed visions of saints
classified as apparition like the Church approved Marian apparitions. Saints had no glorified body unlike the Blessed Virgin Mary. Saints appearances are merely called visions not apparition.
The 4th Dogma of the Assumption stated that Mary was assumed "body & soul". So, in all Church approved Marian apparitions we can be sure that only Mary appeared to visionaries in a glorified body & soul.
All the Saints if ever they appeared in a visions is totally different from Mary as the Catholic Church teaches that all the glorified souls of the Saints will only be reunited to their glorified body in Parousia. So, the visions of accounted Saints is far less than the Sovereign Queen of Heaven and Earth as it does not possessed a glorified body.
997 What is "rising"? In death, the separation of the soul from the body, the human body decays and the soul goes to meet God, while awaiting its reunion with its glorified body. God, in his almighty power, will definitively grant incorruptible life to our bodies by reuniting them with our souls, through the power of Jesus' Resurrection.
But the uniqueness of Mary excel even Jesus Christ apparitions, as Mary First Church approved apparition occurred in the year 40AD while She was still very much alive.
Our Lady of the Pillar' the Church called this "Pre-Assumption" apparition.
St.Joseph also had an approved major apparitions and this would mean that the homily of St.John XXIIII stating the merit of the resurrection of St.Joseph body was true. St.Joseph body was resurrected meaning when St.Joseph appeared in a visions what were seeing is a glorified body and soul like Mary and Jesus.
On May 26, 1960 Pope John XXIII in his homily for the feast of the Ascension of Our Lord made a statement that the Assumption to Saint Joseph is worthy of pious belief (). He also stated that he believed the same privilege was accorded to Saint John the Baptist33. This is the first time that a Pope has ever made a public statement on the subject and the fact should offer great reassurance to those who feel it would be contrary to their religious sentiments to imagine Christ refusing Joseph this crowning grace. Pope John's words are a guarantee that such a belief is truly prudent and therefore can no longer be classified as a "pious exaggeration".
Here's the link on the Church approved apparitions of St.Joseph;
Devotion To St Joseph’s Most Chaste Heart – Approved Apparitions…
Many know about approved apparitions of our Blessed Mother. But only a handful realize that there were apparitions in Itapiranga, Brazil from 1994-1998 in which St. Joseph appeared along with Mary and Jesus.
In January 2010, after much study, prayer, reflection, observation and seeing the growth in the faith life of thousands, the local ordinary, Bishop Carillo Gritti declared a Decree of Worship favoring the Itapiranga appearances and in an earlier document called it of “supernatural origin.”
So, the Catholic Church devotion to the Holy Family is now complete. The Sacred Heart of Jesus, the Sorrowful & Immaculate Heart of Mary and also the Devotion to the Chaste Heart of St.Joseph.