”Ledian is complete garbage, and you’ve got better options then Ariados” -Commeneted by X.
My thoughts exactly. Ledian should never be used, with only 390 BST it is absolutely poor. Even in casual playthroughs. Ariados is a bit better, but you still have better options. For Ledian, you should use Scyther/Scizor. They are absolutely better in everyway, and are very good in game. Here is a moveset.
Scyther/Scizor (Gen 2) @ Silver Powder
Steel Wing - Coverage
Fury Cutter - STAB -While a weak move on the surface, the held item and aand STAB boost will make this very good.
Wing Attack - STAB -Same case as Fury Cutter
Swords Dance - Setup
Now, for Ariados, you got two options. If you want to maintain the bug typing, then Heracross is a good solution. If not, then go with Fearow. I will list movesets for both.
Heracross (Gen 2) @ Really Anything.
Megahorn - STAB
Strength - Coverage
Earthquake - Coverage
Curse - Setup
Fearow (Gen 2) @ Kings Rock
Fly - HM use and STAB
Hidden Power (Ground/Water/Grass) / Return - Coverage
Steel Wing - Coverage
Curse - Setup
In the end, I would go with Heracross and Fearow.
Hope I helped!