Its rather simple actually, Once you know skorupi was in the marsh, save in the lobby, find a seed with your desired spread, preferably frame 200+, daily marsh pokemon are slots 6 and 7 in the area they are found. Once youve found one reset for your seed, then enter the marsh, go to the area you need and sweet scent a pokemon. Catch it and open the menu immediately! Don't give the NPCs a chance to move. Find its 'actual' frame, its in the column next to the method J frame. Then add 9 frames to that (7 frames for the battle/capture and 2 for sweet scent, I had a roamer so I went 10 frames) then journal flip to your target and sweet scent again.