Hmm, that's interesting that some of you are saying that throwing more pikmin would make you more offensive. My immediate response to this question would have been the opposite. A defensive player might be hopping in place and tossing more pikmin. If that's the case, always use pikmin toss as a precursor to your approach. It is good to for racking up damage, but it can also allow you to sit back and chill, the opposite of what it sounds like you want.
Otherwise, there are lots of instances where players relax after completing a combo or wait for opponents to recover. Keep the pressure on as much as you can all the time. And then if you want to get really offensive, start paying more attention to which characters you can edgehog, spike, or otherwise attack outside the bounds of the stage. A risky move for Olimar, but one that can catch people off guard if they're used to an Olimar petrified to leave the ground. Last note: definitely takes tons of practice to be able to pull off those attacks without killing yourself 90,50,25% of the time.