Yeah. I liken MK's quick sword to a Chef's Knife and the Pikmen to vegetables needing to be diced.
Edit: I'm hesitant about giving advice about Meta Knight if you don't intend to use him much. I definitely have a lot of tips to give you, especially things to do better against Olimar, but if you're going to be sticking to Lucas, then my advice for his character below should suffice.
Edit: Ok, I got the chance to watch the videos. I've only watched the first one, but I've got tips for both sides. Olimar is another character I use alot, and I definitely have some tips there to start.
Olimar: Use your Foward-B a lot more. ALOT. When you have distance, take advantage of it by being annoying with those buggers (i.e. Pikmen). They tack on damage quickly and often put the opponent on the defensive even though you may not be anywhere near them. Be mindful of how many Pikmen you have on you so you don't end up helpless.
This way you don't have to move around as much. Olimar is defensive most of the time and should be using his Pikmen to make the opponent screw up (and damage them in the process). Also, his smashes have basically no knockback at low percentages as you can quickly see at the beginning of that first video. Before spamming those, you should be tacking on some more damage first.
Lucas: To be blunt, your approaches were about as bad as they could be. You used your dash attack WAY too much. It's slow. And has a lot of lag. And it's really not that powerful. Worst of all, you were fighting Olimar and often threw yourself into an easy fsmash or usmash.
Lucas has excellent Aerials. You should definitely make use of them by utilizing the SH as an approach. With his disjointed hitbox and decent priority, most Pikmen attacks will be knocked aside. Just be careful of aerials with more lag than others, such as the dair.
Also, Olimar is best at medium range. Fortunately, Lucas is good here, too. Properly spaced PK Fires are excellent for keeping pressure on Olimar without putting yourself in too much danger. PK Fire is stopped by any Pikmen attack (Foward-B or fsmash, for example), but it can also kill all but the Purple and Red pikmen.
Use PK Thunder a lot, like you do, but maybe change the way you use it a bit. You got quite predictable by the end and the Olimar was shielding by the time you blasted yourself into him. Try using the PK Thunder itself as the attack more and make sure you're safe by either knocking him away first and then following up with PK Thunder or by having plenty of distance between you to begin with.
Look up B-sticking. There's a thread by SamuraiPanda in the Brawl Tactics forum about Auto-RAR and other such things. The uses for Lucas are incredible.
Specific advice against Olimar: Whenever Olimar throws a Pikmen, it becomes vulnerable to damage. Almost any attack will kill a Pikmen, unless it's a Purple one. If you find yourself just outside of his fsmash range while he's spamming the Pikmen, take the opportunity to dispatch all the Pikmen lying helplessly on the ground. It's easier with MK because of his faster attack speed, but a dsmash from Lucas should definitely do the trick. The same applies if you ever see a Pikmen running from far away to catch up to Olimar. Feel free to turn around and smack the Pikmen.
