Hmm. For some reason, I have no trouble against Kirby ... One thing to know ... avoid up smashes and PK Thunders when he's above you, because he'll almost always counter with his rock attack, making him invincible and able to bash you through your attacks. When he does use the rock move, try to be near him to either grab or to hit him in the instant he pops out. If he eats you, be sure to absorb any PK Freeze attacks he uses. Also, when he uses his final cutter and lands on solid ground, you can absorb the shock wave.
Pit's a tough one. I like to approach him with neutral aerials. If placed right, they'll go through him and over the top of his shield. Also, if he shields your PKT2, there's certain angles or distances that will go right through and hit him, too. Forward tilts are your friend vs just about any foe. They're very quick and have admirable range, and can be angled up or down. If he's below the stage, I'd say give chase. Pit's flying recovery is easy to cancel, and I believe he only can do it once before having to land. Pit's at his most vulnerable when he's trying to recover, especially when fairly low relative to the stage. Do not try to attack him from above in the air; he's got great counter moves for that angle. If he shoots you as you try to recover (as my opponent always does) be ready to use PK Magnet.
Toon Link - I haven't fought many, but I'd say you should make good use of Lucas's longer-ranged attacks, such as his forward tilt, and dash attack. Also, I bet he's easier than some to land up smashes with. Try to predict or bait him into down aerials, then either dodge and capitalize, or counter with an up smash. Don't challenge him in the air--his range and power will outdo you all the time. If you send him flying, pursue him and try to bounce him off the stage with moves like PK Fire and Thunder, or the forward aerial. Toon Link I think is best suited to aerial combat. His projectiles are inferior to Lucas's, so force him to compete on that level.
Meta Knight -This guy's tough for Lucas (I usually switch to Ness). Projectiles are your friend. As always, try to use your longest ranged attacks to avoid getting near him. As I recall, PK Fire hits him out of his tornado attack. Make good use of PK Thunder while he's in the air. This is one opponent it might not be best to pursue out over the ledge. The multiple jumps and quick, wide-ranged attacks will beat you if you try. Instead, try to PK Thunder or Freeze. Also, I think he's weaker from the bottom, so if he goes up don't let him come down.
I wouldn't consider any of these characters Lucas counters. The ones I have the most trouble with are Dedede, ROB and Ivysaur--characters able to challenge Lucas's range, keeping him at a distance so he can't land his more powerful attacks. Kirby, in particular, I think can be defeated with relative ease once you're used to him.