From Nookipedia, the Animal Crossing wiki
Festivale is a spring event that happens in February or March. Pavé hosts the event in front of Town Hall. During the event, confetti will be raining down from the sky. As some neighbors will point out, there will be no snow or rain during the entire day. Festivale is quoted by Nintendo Power, as an 'all-day festival of color, costumes and craziness!' Festivale is based on Mardi Gras, the last day of Carnival, a festive season occurring before Lent.
In both games that Festivale appears in, the player's objective is to collect specific items (candy/feathers) as requested by Pavé. If the player obtains the items, Pavé will give them an item from the Pavé Series. In Animal Crossing: City Folk, the player must collect candy, and in Animal Crossing: New Leaf, the player must collect feathers.
In Animal Crossing: City Folk during the day, neighbors walking around the town will challenge the player by asking them to play games, with the chance to win candy. However, if the player loses, he or she has to give some candy or 500 Bells to the villager. There is no limit of how many games can be played with the neighbors, but only the ones outside of their homes will offer to play games.
The games are as follows:
The candy the player has won can be given to Pavé, who will exchange it for furniture in the Pavé Series. However, players must have three of the color candy he asks for.
If a player buries a pitfall seed on the day of the Festivale, it may turn into candy the following day.
In Animal Crossing: New Leaf, the event is slightly different compared to the Festivale in City Folk. Unlike the objective in City Folk, the player must collect feathers instead of candy for Pavé. During the day, feathers can be seen falling from the sky along with confetti (the feathers can be obtained using a net). This event has a challenging objective due to the difficulty of identifying the feather color from the confetti. The event can be played with town guests, making it a bit easier to complete groups of feathers by working together.
The villagers walking around the town can be found wearing headdresses with different colored feathers on top of them. They may also be seen singing (whistling) the town tune. Animals inside and outside their homes will both offer to play games with the player to win feathers. Some animals will offer the player a feather without asking for anything in return.
There is a new game that involves the player guessing which way the villager will move his/her head, by doing that at the same time. When a player loses, they simply do not get a feather or they will lose a feather instead of paying 500 bells.
If the player obtains the specific number of feathers requested by Pavé or obtains a rainbow feather, then Pavé performs a dance (or a special dance if the player has obtained the rainbow feather). After Pavé has finished dancing, he will give the player a piece of furniture from the Pavé Series.
Feathers can be collected from the sky during Festivale; players use a net to catch them. After giving the feathers Pavé requested, Pavé will dance and exclaim depending on the color of the feathers given, and he gives furniture from the Pavé Series. Shown below are the available feather colors.
Rainbow is the rarest color. Consequently, Pavé accepts any rainbow feather regardless of what color he has requested.
Pavé will trade furniture for candy as well. However, he asks for three of a candy color: blue, red, yellow and green.