In Pokemon Snap, the Triple Threat Challenge is a request, and to complete this request you will have to go to Founja Jungle (Night) map. Phil saw a Yanmega fly away from the area, so he will request to know if something happened there. After players get the melody player, the request will unlock, which means that you will have to use the melody player during the request.
To complete this request, you will have to head to the Jungle’s Swamp route. Then players will have to uncover some footprints near the Crystallboom just before the Swamp with the help of Illumina Orb. After the footprints are revealed, get onto the swamp route by scanning the footprints.
You should play the Melody to force Yanmega to emerge from the brush to their left and fly away just before entering the swamp. You should play the Melody once again after you have entered the swamp. By doing this, the Yanmega will be summoned, and an Ariados will emerge from a tree hole. Hit the Ariados with the Illumina Orb and the Pokemon will start fighting. Take a photo of them as they do so.
You should aim Ariados in the shot, and once the expedition is over, hand in the photo to complete the Triple Threat Challenge.