Keepers from Season 1 don't have to participate, but their efforts from the 5 days that Season 1 existed will be recognised. A Keeper may choose to burn their Season 1 Munchables to guarantee a payout of Munch Points that will be recognised for Season 2.
This mechanism works by valuing the Keeper's Munchables based on their hatched state and rarity. The burn is a 1-time operation. The calculation methodology is explained below.
Calculate the Adjusted Rarity Factor
The logarithmic rarity factors for each type are calculated using the total number of each Munchable type from season 1:
First, we calculate the sum of all adjusted rarity factors:
8.918+9.452+8.425+7.476+5.976+3.932=44.179
Next, we calculate the points allocated to each type based on their adjusted rarity factor proportion of the total pool of 50,000,000 points (this is 5 days of rewards using the Season 2 daily payout of Munch Points of 10,000,000):
Points for Type=Total Adjusted Rarity FactorAdjusted Rarity Factor×50000000
This shows the individual payout for burning a Munchable based on its type. Note that Unrevealed Munchables are paid slightly higher than Commons to respect the fact that their rarity was undetermined.