Microtransactions in Chocobo GP are summarized as...
This is a full priced game but it is littered with microtransactions. The game offers multiple currencies, some are earned in-game, others have to be purchased with real money. Each currency is used to unlock different cosmetics and not all currencies can be used to unlock all cosmetics. The primary premium currency is called Mythril. This premium currency comes in awkward quantities that force you to spend more for less.
The game offers a premium Battle Pass. This is a slow grind, but levels can be purchased for real money to instantly get access to the rewards. The battle pass is a timed exclusive. If you do not finish it in time you will lose access to everything you didn't unlock (but still paid for). The Battle Pass includes more than just cosmetics, it also includes popular playable characters as higher level rewards.
The first battle pass is technically "free", you get enough Mythril to unlock the battle pass if you log in during the first season. However this Mythril expires in 5 months time. Mythril you purchase yourself does not expire.
"Gil" is a currency that is earned in-game and is used to purchase some cosmetics, but is primarily used unlocked some playable characters. This currency is earned at an extremely low rate. However this currency can also be earned through the battle pass at a higher rate, but of course the battle pass is not free.