Mmm... the scarves are given out by the leader of the pokémon fan club (a man, not a woman). You definitely only need to have maxed out one contest stat to get the scarf. It's hard to max out in two stats on the same pokémon, unless you are able to mix 4-way with other trainers and have some pretty rare berries. Scarves are held items, so you can swap them after they have been awarded - you only need five pokémon, each maxed out in a different contest stat.