Ah the good old days of my Lucas skrubbishness. Although I no longer have Lucas, I still know a lot about the little guy. Lucas used to be my main, and therefore I read up on all these guides. From what I learned, these are the most common mistakes of Lucas beginners:
-Use of PK Thunder instead of Rope Snake
-Not learning bread-and-butter combos
-Trigger Happy- overly committed to an approach or tactic cough Up Smash
-Playstyle- too aggresive
-No use of PK Fire or Zair
-The worst mistake- Assuming that Lucas is a Ness clone
First of all, Lucas and Ness and completely different. Ness is more combo oriented, aggressive, and an all-around troll. Lucas is a defensive spacer. When you play Lucas, you should always have a defensive mindset. He is built to stop opponents in their tracks. If you catch yourself getting too frisky, calm down and regain your thoughts.
Down Throw -> Nair: Amazing in the neutral. Easy damage, can chain into itself. Keep in mind that Lucas's Nair can be used as well for approaching, specifically, platforms.
Lucas's Nair also has a very easy auto-cancel. I often use it instead of plain old tech, because sometimes I get too predictable.
Zair is Lucas's best move. AMAZING RANGE. Very fast, little landing lag. It's perfect for zoning your opponent. USE IT, A LOT. It's more reliable than PK Fire. However PK Fire is amazing, in the sense that it deals decent damage and is hard to counter. Trying mixing up Zair and PK Fire. Specifically, PK fire when they are approaching on ground, as the PK Fire will easily end their plan. Zair for aerial approaches.
Lucas's best kill move is his Up Throw, or Back throw, if near ledge. Forward throw is useless and Downthrow is your combo starter. Dont stale out your Up throw. Up throw kills most characters at 140 - 160% When you do hit that 140 threshold, don't go "trigger happy" and start throwing out grabs here and there. You MUST be patient. Side Smash is also very good, but makes sure you hit it.
When edge guarding with Lucas, your best bet it PK Thunder. What you'll want to do is a figure-8 around the ledge, making it impossible for your opponent to get pass without eating some of your PK Thunder. It wont kill most characters, but can be fatal to some cough Little Mac. Do a figure 8, so that the tail is moving towards the bottom of the stage. Down Smash at the ledge can easily catch most characters, minus the teleporting ones, and knock them off, to the point where recovery is impossible.
If you have trouble getting grabs, then try Pivot Grabs. Lucas's Pivot Grab is very fast and reliable. Also Pivot forward tilt is good at catching your opponent off guard.
Lucas has amazing tilts. Although you wont be using them as much as Zair or PK Fire, his titls are extremely reliable and safe. F-tilt is good at whacking your opponent, usually catching them getting on a platform. Up tilt is a nice mix up when things get too close for comfort. Down Tilt is a combo starter and can potentially ledge guard.
Lucas has equally amazing aerials. His Up air can kill at high perfect (Down throw to up air is a nice killing combo). Forward air is the equivalent of his f-tilt, but in the air. It is used for catching your opponent off guard. Hitting the sweetspot can knockback them back really far, whereas the sourspot and lead to other aerials. Back air is a nice spike and is used for offstage edge guard, but Dont use it for anything other than that. Down Air is amazing, especially his Rising Down Air, which provides great shield pressure and cam catch opponents getting on a platform.
When recovering, prefer using Rope Snake over PK Thunder, since it is safer and faster. Also too many things can go wrong with PK Thunder (Villager or Ness), and only use it when low, as it can travel VERY far. Just remember, only use PK Thunder when you have no other choice.
From his specials: PK fire is great, PK Thunder is nice at ledge guarding and recovery. PSI Magnet has very few uses, and PK Freeze is pointless.
For controls, I recommend setting the C-Stick to Attack and take full advantage of Lucas's tilt and aerials. Also try to use Tap Jump Off since it only makes combos easier. You can set your C-Stick to Special, but the only advantage to this is Wavebouncing, which isn't that big of a deal in the metagame. There are a plethora of advantages from setting it to Attack.
Skills that you should learn:
-Short Hopping
-Nair autocancel
-Lucas's Bair spike
-Pivot Grabbing
- Dash Dancing and Perfect Pivoting (If you want to go that far)