As this is an RP site which is meant to give free reign to the players (to an extent,) it doesn't particularly matter how you use a move as long as it has been shown it can in fact be used that way through mechanics or some form of in-game description. If one game says it does this and another says it does that, it can do either. It's all up to choice. There are many instances within the main games, the anime, and the manga in which moves don't always do the same thing, so it's reasonable to allow people to use a move how they see fit as long as it's deemed fair.
For instance, it's stated in the Pokedex entries of Double Team that the user moves very fast, creating an afterimage at its starting point. Yet in the anime and manga, it has at times been used to create multiple fully mobile long-lasting copies, seemingly without any quick movements involved. Since it's not really fair to pick and choose which one is allowed and which one isn't when neither are ridiculously strong, both are allowed and it's up to personal preference of the individual.
TL;DR you can use either.