You ask, Niantic delivers. The Pokemon Company has updated the Candy XL feature, and now we can receive them from many activities, including walking and trading.
This update is now live on the game, and it will allow us to obtain Candy XL through walking your Buddy, trading, catching Legendary, Mythical Pokemon, and evolved Pokemon.
If you have a Stage 1 Evolution, you will get one Candy XL; Stage 2 Evolution will give you two Candy XL, and catching Legendary or Mythical Pokemon will grant you three Candy XL.
As for trading, Niantic stated that the greater the distance between Pokemon catch locations is, the bigger amount of Candy XL you will gain.
Hope you like this update, but if you do not, comment down below your opinion on Candy XL.