There is not a clear and precise rule, which is always repeated.
Most likely though:
1) when Bitcoin gets up strong and so all the other coins come down, as in these weeks that everyone wants to have the Bitcoins and sell the other coins for them.
2) when Bitcoin drops sharply and so much then all the other coins come down because it means there is fear and panic in the market, and investors sell everything at any price and expect better times, "parking" the money in FIAT.
3) When Bitcoin rises slowly or moves shortly then all the other coins go up so much, and there will be coins that will make x5 - x10 - x50 even in a month
I believe that by the end of 2017 all other coins will suffer for the strong speculation on the Bitcoin blockchain
![Wink](https://bitcointalk.org/Smileys/default/wink.gif)