Yashoda, churning, feeds Krishna and puts him down when the milk boils over. Angry, he breaks the curd pot and feeds butter to a monkey from a mortar. She chases and catches him, and decides to tie him to the mortar, but each rope is two fingers short; when she is exhausted he allows himself to be tied, and is called Damodara. He crawls between two arjuna trees, pulls the mortar through and uproots them, freeing Kubera's sons Nalakuvara and Manigriva from Narada's curse.
Bhagavata Purana 10.8 to 10.10, the butter thief and Damodara (English translation, Vedabase) § 10.9; Bhagavata Purana 10.8 to 10.10, the butter thief and Damodara (English translation, Vedabase) § 10.10
The gopis complain to Yashoda that Krishna lets the calves loose, steals curd and butter, and when pots hang out of reach climbs on mortars or on his friends' shoulders and pierces them from below. So the pots are hung higher and the boys build ladders of themselves. On the day after Janmashtami Maharashtra hangs a pot of curd high over the street, and teams of Govindas build human pyramids to break it, to cries of Govinda ala re.
A custom: the butter thefts acted out as a public game.
Bhagavata Purana 10.8 to 10.10, the butter thief and Damodara (English translation, Vedabase) § 10.8; Krishna Janmashtami, Wikipedia
Sources: Bhagavata Purana 10.8 to 10.10, the butter thief and Damodara (English translation, Vedabase); Krishna Janmashtami, Wikipedia
The Asura Pralamba joins the cowherd boys' game disguised as one of them, loses to Balarama and has to carry him, and runs off with him growing huge; in the Vishnu Purana Krishna reminds Balarama of his own nature, in the Bhagavata he remembers alone; he kills the demon.
Balarama, teacher of the mace to both Bhima and Duryodhana, refuses to fight in the Kurukshetra war and goes on pilgrimage; he returns for the final duel, and when Bhima strikes below the navel he rushes at him with his plough until Krishna holds him back, then leaves for Dwaraka. In the Bhagavata he tries to stop the duel and fails.
King Yadu meets a young wandering sage who is happy and fearless, and asks who taught him; the sage names twenty-four teachers, the earth, the wind, a pigeon, a python, a moth, a courtesan named Pingala, a girl's bangles and a spider among them; tradition calls him Dattatreya.
The boy Krishna leaps into the Yamuna pool poisoned by the serpent Kaliya, is bound in his coils while Vrindavan weeps on the bank, then dances on his hoods until the serpent's wives beg for his life, and sends him back to the sea.
Twice a year, at the end of the Painkuni and Alpassi festivals, the images of Padmanabhaswamy, Narasimha and Krishna are carried from the temple to the sea at Shanghumugham, across the runway of Thiruvananthapuram's international airport, which closes for the evening.
In Jayadeva's Gita Govinda Radha, finding Krishna dancing with others in spring, withdraws in jealous grief until her friend carries messages between them and Krishna, repentant, begs her to set her foot on his head; the devotional legend says Jayadeva dared not write that line and Krishna came and wrote it himself.
Vrishabhanu finds a baby girl on a lotus in the Yamuna at Raval; she keeps her eyes shut until the infant Krishna is brought before her; the Brahma Vaivarta Purana adds that she came from Krishna's own left side in Goloka and was born on earth through a curse.
Krishna, now in Mathura, sends Uddhava to console the women of Vraja with talk of the formless god; one of them, speaking to a bee, mocks the messenger; the Bhagavata never names her but commentators and poets made her Radha, and Surdas's Bhramar Geet turns the scene into the gopis' refusal of Uddhava's teaching.