Re: Chain-breeding in White, please help!
Females can't pass on moves. So you won't be able to get Giga Drain like that. If you have access to 4th gen games, it's probably easier to breed Teeter Dance onto a Lotad via Cacnea and then teach that Lotad Giga Drain via TM.
Otherwise this should work...
Breed male Spinda with female Cacnea to get male Cacnea with Teeter Dance
Breed male Cacnea with female Oddish to get male Oddish with Teeter Dance
Level up Oddish to learn Giga Drain (Level 37)
Breed male Oddish with female Lotad to get Lotad with Teeter Dance and Giga Drain