@Noqanky:
Huh, when you put things in the context of what Caesar said it does make a lot of sense. Then to sell the weapon he just sells the axolotl apples with the formula that was in the candy and some gas. It is nice though that he went ahead and got rid of the main complication for the Straw Hats which was fighting a huge axolotl made of a toxic substance that explodes.
Also, CC isn't really explaining all about Devil Fruits. There definitely has to be more to them. So Vegapunk will still get some fun explaining.
Only one apple transformed tho.
Maybe he simply needed a way to create the super deadly gas, and abused a zoan df to combine certain effects.
Like:
Step A: Create deadly gas (4 years ago)
Step B: Combine deadly gas with a zoan df
Step C: The now created zoan df is able to incorperate other kinds of gas by simply eating it. A result that can't be achieved through research or so, because it defy's the laws of nature.
Step D: Create another type of deadly gas, wrap it up with a random df and let the gas zoan consume it.
Step E: Gas zoan absorbs the gas, creates an even more deadly mix…but dies shortly after because the second DF starts doing it's magic (Lucci said it takes a while before DF powers awake).
Step F: Super deadly gas is now all over the place, the Axolotl DF transferred back to one of the preparred apples. Time for CC to collect his loot. He can re-capture the super gas with his own Devil Fruit, and the Axolotl DF isn't lost.
Step G: Sell the weapon in barrelform or whatever. Repeat the process with the Axolotl DF for future sales.
We shall meet again, Smiley.