Dreamy Mates (ドリーミーメイト Dorīmī meito) are made by the fairies in the Miracle Dreamy Kingdom. They are plush kittens that can go to the world of dreams. They have human partners which are called Dream Partners as mention in Episode 1 and Episode 20.
Mew can go to the world of dreams by connecting her heart with her partner Yume Hinata. Only Mew has the power of Dream Synchro and without Mew, they cannot use Dream Synchro, as mentioned by Suu in Episode 12. Only Mew's partner, Yume Hinata, can go with her with other Dreamy Mates as they go into someone's dream, according to Peko's Care Guide in Episode 5.
Dreamy Mates are dropped from the sky and their Dream Partner would find them. They cannot expose their true identity to anyone who is not a Dream Partner, or they will return to being a normal stuffed animal, according to the Queen in Episode 2.
In Episode 4, it is revealed that to awaken a Dreamy Mate, the power of Mew and her partner is needed, in other words, they need to use the Mewkle Stick. It is the same for Suu in Episode 6 but it seems that both Nene and Rei did not need the power of the Mewkle Stick to awaken. As shown in Episode 13, Yume just used the Mewkle Stick to purify the Black Abyss in Tokiwa's dream in which Nene appears after Yuni's defeat. In Episode 20, Rei was awoken after the Queen Above the Skies visited Asahi in his dream to talk to him which Rei also appeared in and when Asahi awoke from his dream, Rei was talking to him.
Known Dreamy Mates
Each Dreamy Mate has a Care Guide that tells their Dream Partners about them.
Half of Nene's Care Guide are divinations as shown in Episode 13.