Read the whole bio for zero suit samus
It says that she isn't a pure character addition, so "under certain conditions" she'll take off her power suit. If she was a separate character they would not have said that.This isn't a pure character addition. Rather, under certain conditions, Samus will "remove" her Power Suit. Whoa! That's a woman under there!
Naturally, Zero Suit Samus loses power and stamina, so she should fight using the speed she gains instead.
Also, her gun transforms and can be used as a whip. Of the two, one might consider the whip to be her main weapon.
And don't worry—you'll still be able to play as standard Samus, too.