Daisy originally applied to be allowed to take part in Melee. At the time, she did not have much of a following and therefore her chances of getting in were rather slim. After she had confirmation that she was not going to be in, she met Snake, and the two clicked instantly and fell in love. Daisy and Snake spent the years between Melee and Brawl together.
Brawl finally came around and the two both applied to get into the game. They both made an agreement that if one of them was not accepted into the game, neither of them would take the place. However, Daisy was not accepted into the game, but Snake was. Snake decided to make up a lie to Daisy and told her that he was going on an important mission to save the world, and Daisy fell for his ruse at first. When Brawl was released, Daisy found out the truth, and could not forgive Snake.
Between Brawl and Smash 4, Daisy spent her free-time alone, in despair and utter betrayal, usually playing sports. One day, whilst practicing tennis, she met Waluigi and the two became close friends who would always play sports against each other. Times were good for Daisy until Smash 4 came around. She applied once again, and, as usual, did not get a place in the game.
After Smash 4 was finalized, Daisy was invited to the Cut Crew. This was a crew led by Pichu, a former veteran to the Smash series. The group was for all former members of Smash who were removed or all who had a large following but were not added to the game. The crew had existed since after Melee, and had several members, with Daisy being the newest.
Daisy noticed that her friend Waluigi was also here; he had been invited a bit earlier than her. Also here was Snake. Daisy openly had a disgust for Snake for his utter betrayal against her, and did not wish to be around him.