"While Jon Snow is standing, he is considered participating in each challenge in which you control another attacking [First Watch] character."

Does he add his 4 Strength to each challenge, regardless of type, or only the challenges on which he has symbols (i.e., just Intrigue on an unmodified Jon card)?

Thanks in advance!

"While Jon Snow is standing, he is considered participating in each challenge in which you control another attacking [First Watch] character."

Does he add his 4 Strength to each challenge, regardless of type, or only the challenges on which he has symbols (i.e., just Intrigue on an unmodified Jon card)?

Thanks in advance!

Having an icon is not required in order to be "participating" in a challenge, just for the process of declaring a character. You'll find this evidenced by entries like the following:

xxOnce a character is participating in a challenge, losing the challenge icon of that type does not remove the character from the challenge

So, yes, as long as you have an attacking NW character, Jon Snow is not only adding his STR, but actually a part of the challenge (his keywords would matter, as would his status as participating - he could be hit, for instance, by Dracarys or Ghaston Grey)

Thanks for both the answer, and the explanation, which helps me better understand the nuances of the declare/participation aspect in general. Much appreciated!