Lucky Pokémon

Lucky Pokémon are special Pokémon that have minimum IVs of 12/12/12 and costs half as much Stardust to power up.

Obtaining Lucky Pokémon
When trading Pokémon, there is about a 5% chance that Pokémon can become a Lucky Pokémon, which increases based on how long that Pokémon has been in the Trainer's box; the older it is, the higher the chance.

When traded, both Pokémon always either remain normal, or become lucky.


 * There is a way to guarantee a Lucky Pokémon and that is by doing a trade with a Lucky Friend, which is a special upgrade to a Best Friend that has about a 1.1% chance of happening when you interact with them for the first time each day.

The Stardust cost for powering it up will be reduced by 50%, which means they can reach a higher CP much faster than other Pokémon. This cost reduction stacks with that of being Purified, making a Lucky Purified Pokémon far cheaper to upgrade.

Odds
According to research by The Silph Road, the odds are based on the ages of each of the Pokémon being traded.

Assuming that one is less than a year old, the odds are as follows, based on the age of the other being traded:


 * Less than 1 year old: 5%
 * 1 year old: 10%
 * 2 years old: 15%
 * 3+ years old: 20% (research so far suggests that 20% is the cap)

Additionally, if both Pokémon are at least a year old, the odds are boosted further (up to the apparent cap of 20%).


 * The findings suggest that the Lucky Rate may be based on the combined ages of the two Pokémon. Thus two 1 year old Pokémon have the same odds as a new with a 2 year old Pokémon.

Note: This research is currently ongoing, but these are the findings thus far.

Limited 100% Lucky Trade
Other than trading with a Lucky Friend, there is another situation where a Lucky Trade is guaranteed, introduced as a promotion to get lapsed players back into the game. The requirement are quite strict :


 * One of the Pokémon being traded must have been caught during July or August 2016 (the first two months from the game's release)
 * The Trainer sending the guaranteed Lucky Pokémon must have been involved in fewer than 10 trades (as either a sender or recipient) where at least one party was guaranteed.
 * The Trainer receiving the Lucky Pokémon does not affect this trade, though it will increase their own count of guaranteed Lucky Trades.
 * It is currently unknown if Lucky Trades from being Lucky Friends impact this count, but there have been reports that they do.

Characteristics
On the Pokémon collection page Lucky Pokémon have gold glowing backgrounds behind their sprites.

In Pokémon summary screen, Lucky Pokémon have a green label below their name, indicating that they are lucky. Their background is gold and features shimmering effects &mdash; this effect is also visible in their Pokédex entries which have navy blue background instead of purple. The number of each Lucky Pokémon a Trainer has obtained of one specific Pokémon is also tracked in the Pokédex.

Trivia

 * Although Pokémon turn into Lucky Pokémon at random when traded, the longer a Pokémon has been held onto, the greater the chances that they will become Lucky Pokémon.
 * Before September, 2018, Lucky Pokémon had a minimum IV floor of 10/10/10.
 * The sparkly effect of a Lucky Pokémon on the Pokédex actually extends slightly into the entries immediately before and after it.
 * The background of Shadow Pokémon completely override that of Lucky Pokémon on the same Pokémon. However, Shadow Lucky Pokémon can no longer be obtained as Shadow Pokémon were made untradeable.
 * The background from types used to be visible behind the Lucky Pokémon effect; this has since been changed and the type background cannot be seen on a Lucky Pokémon.
 * In September 6, 2018, Pokémon GO announced in Twitter that trading a Pokémon that was caught or hatched within July 2016-August 2016 will always guarantee a Lucky Pokémon.