Crystal Dust early X Attack usage

Crystal Dust early X Attack usage

These calcs don't consider Bugsy's other Pokes (Metapod/Kakuna)

Option 1: Use X Attack on Bugsy
Scyther: X Attack, Leer x 2, Scratch x 2 (93.75% to 2HKO)
Gastly: Water Gun, Fury Cutter x 1-3
Bayleef: Fury Cutter x 2-3
Zubat: Scratch x 2

No heal turns likely unless Scyther crits or you miss the range (1/16)
Total turns: 12 (5 on Scyther, 5 on Gastly & Bayleef, distributed depending on what happens on Gastly, 2 on Zubat)
---Bayleef 6.25% OHKO if 3 FCs used on Gastly (in Overgrow if it lives)
---Bayleef 100% 2HKO if 2 FCs used on Gastly (this is optimal and most likely to occur)
---Bayleef 100% 3HKO if 1 FC used on Gastly, but will be in Overgrow after the 2nd Fury Cutter!!
---Bayleef 0.02% 3HKO if Water Gun crit on Gastly, will 99.98% be in Overgrow after 3rd Fury Cutter
-------better strat if crit gastly is to Leer, then Fury Cutter x 3 on Bayleef, will 5.47% be in Overgrow after 2nd Fury Cutter

Option 2: Use X Attack on Rival 2
Scyther: Leer x 4, Scratch x 2
Gastly: X Attack, Water Gun x 2
Bayleef: Fury Cutter x 3 or Scratch, Fury Cutter x 2 (34.25% to 3HKO)
Zubat: Scratch

Heal turn likely on Scyther. The only way you do not heal is if he does not crit and only uses Quick Attack he will get six turns - you have 55 HP and he does 7-9 with QA (11-14 after 1 Leer or 13-16 after 2 Leers). This is unlikely, especially if you take some damage from Kakuna and/or Metapod.
Total turns: 14 (7 on Scyther, 3 on Gastly, 3 on Bayleef, 1 on Zubat)
---Bayleef is 5.47% to be in Overgrow after 2nd Fury Cutter

Overall: Using the X Attack on Bugsy is faster overall by ~2 turns, but might be riskier.