The best way to practice would be to netplay/wifi/local fights with someone else.
But, a good way to learn alone would be fighting lvl 9 cpus that you find really hard to deal with (personally, i think level 9 cpu peach is a MONSTER!). Also use other characters to fight against lvl 9 ike, this way you learn the strong/weak points of the character you are using and Ike!
I hope I helped you, Good luck!