I am looking at Knight of Flowers TftH

Knight of Flowers: Response: After you win a challenge in which Knight of Flowers attacked or defended alone, he claims 2 power.

And I am curious what it means to attack or defend alone, but more specifically how KoF interacts with characters declared as naval attackers/defenders and how KoF interacts with characters that are removed from the challenge.

I saw this in the naval enhancement rules but am not sure if it pertains to this situation:

"Any character declared as an attacker or defender through the [Naval] enhancement allows players to trigger responses off a character being declared as an attacker or defender respectively."

Based on precedent, the game has no memory of characters being in a challenge if they are removed from it. You would need to check the restriction at the time that you go to trigger the response. If he is the only one in the challenge on his side (be it attack or defense), you can trigger his ability. What this means, however, is that if any other character joins the challenge on his side and is there through the resolution, the play restriction will not be true when you go to trigger his response. A couple of preemptive responses here; his response would be triggered in the response window of challenge resolution as this is the only time when "after you have won a challenge" is true (naturally, not saying you didn't know that), and even if there was just one other character present on his side and they were killed somehow (claim, deadly, etc), they would still be on the table until step 6 of the framework, and so would still be there to block this response.

J_Roel said:

How I wish there was a thumb or upvote system, this seems spot on to me.