Olimar seems floaty for me and sometimes his d-smash doesn't always follow top priority and i tend to get juggled sometimes which causes problems for me, other wise i'm fine. How would i counter these juggles especially lucas's u-smash with the ice.
Hi there, mate. I had the same problems as you, at first. A good way to break out of a juggle is to be unpredictable. Do something weird that will make your opponent go "What the?". For example, while you're in the air, and your opponent is under you, try moving left and right while you're floating down. Your army of Pikmin will trail behind you, making a pretty cool zig-zag sort of design. Your opponent will not be able to predict where you will land as easily, and you will finally have an opportunity to get back on the ground and PUNISH!
Another tip is to use Olimar's whistle while in the air. Spam it! Move left and right while floating down, and throw in a couple of whistles. The idea is to confuse your opponent, and he will probably be thinking "What is he doing?". That's exactly what you need to get out of a juggle.
With Lucas, just don't go directly above him. Lucas has an arsenal of attacks that he could do to pulverize people above him. While in the air, try gliding down towards Lucas's side, and attack him diagonally with a Forward-Air attack.
I hope that helps.