Upgrades

There are two types of upgrades that can be made to pixies: Rank and level. Upgrading a pixie's rank raises their max level. Upgrading a pixie's level adds experience points to them. Both of these types of upgrades require other pixies to be used.

Upgrading Rank
Upgrading a pixie's rank increases the max level a pixie can reach, or its rank. When upgrading a pixie's rank, at least one other pixie must be used (depending on the rank of the pixie being upgraded). Afterwords, these pixies that are used to upgrade the pixie's rank, colloquially "sacrificed", will not be able to be used anymore. When a pixie's rank is upgraded, their level resets to 1.

One-star pixies require one other one-star pixie for their rank to be upgraded.

Two-star pixies require two other two-star pixies for their rank to be upgraded.

Three-star pixies require three other three-star pixies for their rank to be upgraded.

Four-star pixies require four other four-star pixies for their rank to be upgraded.

Five-star pixies require five other five-star pixies for their rank to be upgraded.

Six-star pixies cannot have their rank upgraded.

Upgrading Levels
Upgrading a pixie's level adds experience points to a pixie. This requires the use of another pixie to be "sacrificed." Just like when upgrading a pixie's rank, when another pixie is used to upgrade a pixie's level, that pixie can no longer be used anymore. Pixies used to upgrade another pixie's level must be a lower level than that pixie. However, they can be any rank.

Common pixies, or one-star pixies, give 2500 experience points.

Rare pixies, or two-star pixies, give 5000 experience points.

Mythical pixies, or three-star pixies, give 10000 experience points.

Divine pixies, or four-star pixies, give 15000 experience points.

Shiny pixies, or five-star pixies, give 20000 experience points.

Six star pixies give 25000 experience points.

Trivia

 * Before release, there was a bug in which a pixie's rank did not reset when it was upgraded. Many testers this to their advantage.