Actually, Fire/Flying has 6 resistances (2 doubles to Grass and Bug, and 4 singles to Fire, Fighting, Steel, and Fairy), Electric/Flying has 5 (Grass, Fighting, Flying, Bug, and Steel), and both Psychic/Flying and Ghost/Flying have 3 resistances (a double to Fighting and 2 singles to Grass and Psychic AND a double to Bug and 2 singles to Grass and Poison respectively).
So Baile Oricorio has the most, then Pom-Pom, and finally Pa'u and Sensu.
As for weaknesses, Electric/Flying has 2 (Ice and Rock), then Fire/Flying has 3 (Water and Electric are 2x and Rock is a 4x), and both Psychic/Flying and Ghost/Flying have 5 (both are weak to Electric, Ice, Rock, Ghost, and Dark).