ChosenUnlock
Chosen's current unlock requirement has not been independently confirmed. Its Legendary offer is an effect after selection, not evidence of the requirement to unlock the genetic.
Genetics
Chosen: New Legendary Evolutions
In Version 1.2, Chosen offers 3 new Legendary Evolutions; these cannot be upgrades or Branching Evolutions. Official 1.2 notes
ChosenFAQ
Does Chosen give a guaranteed offer every three levels?
megad16’s v1.0.1 evaluation places the guaranteed Legendary offer at the third level-up. megad16 · v1.0.1 review Do not plan around another guaranteed offer at levels 6 or 9: the available sources describe the third level-up, not a recurring three-level interval.
Can Chosen upgrade an Evolution I already own?
When it appears, compare the new Evolutions with your abilities and free slots; in Version 1.2, it cannot upgrade an Evolution you already own.
Sources
The official 1.2 patch confirms three new Legendary options and their exclusions, but gives no repeat interval. The third-level-up timing comes from megad16’s earlier v1.0.1 evaluation; a later player discussion identifies the mistaken every-third-level reading. These sources do not confirm the unlock requirement.
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Why a challenge can exclude Chosen
In the official July AMA, game director Denis explained that Genetics or Evolutions are removed from a challenge’s pool when their behavior conflicts with that challenge. He used Chosen’s three Evolution choices as an example of a conflict with a challenge that restricts those choices. An unavailable Chosen option can therefore be a rule-compatibility restriction, rather than a statement that the Genetic is too strong. The explanation does not provide a permanent ban list for every challenge. Official July AMA · Denis
Update history
: Added game director Denis’s July explanation of challenge-pool exclusions caused by conflicting rules, keeping the Chosen example separate from an unverified complete list of banned challenges.