I'm a Lucas player, and I feel that this article misses a few key points.
PK Fire is an amazing move. It can be used to repel opponents, and it does exceedingly well at that. When a team mate is too close to a melee character it's a quicker resolution than PK Freeze. It can be used to push items such as barrels or explode dangerous items quicker than other means. Ife used in midair, upon landing there will be no recovery.
If you face an opponent directly often they will charge at you along the ground. If you do a short jump towards them and use down+a, you can sail over their heads while Lucas issues 3 short kicks in their direction. Often you'll connect because it's not an expected strategy, and failing that you'll avoid whatever they tried to do. Throwing a PK Fire back towards them just before you land often will catch them off guard too (Note that if you fire too late PK Fire won't launch at all, but you'll still need to recover). Alternatively, try a PK Barrage or PK Fire at a charging enemy.
The PK Thunder technique can be used to snipe the Final Smash trigger; just wait until your opponents have tapped it a couple of times, and angle the PK thunder so it either pushes it closer to you - or somewhere that no one else can reach it. Similarly, use environmental triggers or detonate explosives.
The Flying Electric Tackle is hard to pull off against good players. These players will be able to position themselves in such a way that they're either too close for you to use the tackle, or too far away that they'll be able to move out of the way and/or counter effectively. However, it can be used effectively against edge guarding; it will negate almost all enemy attacks.
Personally, I believe that the author overstates the use of PK Freeze.