some of them doesnt have wallet so where to store ?
And why would anyone buy coin which doesn't have wallet? Storing on exchanges is not safe, just read all the bad user experiences(etherdelta hack - "i lost tokens", "poloniex don't let me to withdraw", "waiting for bittrex over a month to withdraw" "yobit is holding my coins for several months" and so on). You don't know what can go wrong with exchange, it is best to keep your coins in your wallet.