Rapid Spin's a fairly weak move that allows a Pokémon to get out of partially binding moves (like Leech Seed, Fire Spin, or Sand Tomb) or entry hazards (Like Spikes, Stealth Rock, or Sticky Web).
Here's the reference page if you wanna know more.
In other news, we've hit the 30 page limit! Time to move on to the third OOC thread and lock this one up