With this being the case and the fact you can earn lunchboxes for quests, it would seem if youre willling to spend money on the game then buying nuka cola quantum (for instant travel time) would be more beneficial than buying boxes! As with many of the other achievements, all 20 dwellers must be in a single vault. EDIT: Sasha has mentioned in the comments that there are at least a few quests where legendary dwellers can join your vault upon completion. The weapons and outfits they carry will add to your percentage for their respective achievements. While high numbers of legendary boxes are possible, the consensus from comments seems to be around 1 dweller per 20 boxes) Luckily boxes can also be earned through quests and objectives, so keep hammering at those and hope to get lucky! As a side note almost all legendary dwellers come with legendary outfits, weapons or both. (Note: it seems I got incredibly lucky with my first set of boxes, Ive since opened about 40 more and got no dwellers. You may get more and you may get less, but either way youre looking at a fair amount of money if you intend to get this solely through purchasing lunchboxes.

I bought 40 as a test and ended up with 8 legendary dwellers. The only way of getting legendary dwellers is through lunchboxes. While this was possible in the early days of the mobile version, it is now confirmed that in all current versions of the game the only way to get legendary dwellers is lunchboxes.

The chances are incredibly slim, and hard numbers on chance are difficult to come by, but 3 merged radio rooms fully upgraded and staffed with high charisma dwellers will increase the odds. While this may make the achievement seem worse, I have James twice and can confirm duplicates do add to your percentage towards this achievement! As far as getting the legendary dwellers, it is entirely possible to have them show up at your vault door. There are 23 legendary dwellers in the game, all of which are characters from the fallout series.

This achievement is completely luck based and as such will either come relatively quickly or be one of the last you unlock.

Fallout shelter baby dweller luck