Vine Whip is Ivysaur's Up Special Move. Only seen in a screenshot, it appears that a vine extends upward from Ivysaur's flower in order to do a Tether Recovery. When Ivysaur is on the ground Vine Whip is used as an actual whip, like Sheik's Chain
Origins
In the Pokémon games, Vine Whip is a fairly standard grass type move. It is very frequently seen being used by Ivysaur and its evolutions in the anime.