Out of every shipping advance has the most hints, dawn and ash really didn't have any real hints at all, the only reason why it survived was due to dawn having no major love interest, unless if you count kenny, which she did call him handsome, and misty had no major love interest at all to, and to add fuel to fire 4 kids decided to become pokeshippers themselves and changed many lines to hints, which is the only reason why i believe pokeshipping is the biggest main ship, everyone fell for the lie, advance was a tough one to follow in the dub and seeing as 4 kids were so pro "Pokeshipping" they changed many lines between ash and may, in the end advanceshippings biggest disadvantage is contest shipping but that shipping died when may returning when she referred drew as a rival instead of a friend.
And the 9th movie still remains the only clear shipping moving to date, unless you don't follow the big 4 (Poke,Advance,Pearl,Negai) then the 5th movie would be XD