If what Meowth346 says is correct, Japanese pokemon centers will be giving out Pichu eggs with Teeter Dance. This makes Raichu much more useful in RS. Here's my 2v2 combo:

Raichu@Leftovers
Rain Dance
Thunder
Teeter Dance
Light Screen/Agility

Slowbro@Chesto Berry
Surf
Ice Beam
Calm Mind
Rest

Although I don't know if this move will be released outside of Japan, it's fun to think of nonetheless.