[Question] Hold up

[Soloist]

So if using dragonslayer magic would have caused natsu wendy sting rogue and gajeel to dragonify but that was stopped by their dragons how come cobra and laxus didn't need dragons inside them to keep them from turning into dragons even when they've probably used just as much dragonslayer magic as as the first and third generation.

 

[Goetia]

I think being artificial Dragon Slayers has something to do with it, but I could be wrong.

 

[Kingu]

Probably the Lacrima.
I mean the rest were taught DS magic.

 

[Kai NB]

I'm gonna assume the Dragon Lacrimas already provide the necessary antibodies

 

[Memento Mori]

Like people above me said already,they are the artificial dragon slayers.They didn't learned it from directly Dragons but got the necessary power through Lacrima which made them second generation Dragon slayers.If you look at it then there is a difference between Artificial an Natural.

 

[KayaUzumaki]

I'm in agreement with everyone else above. The whole idea in a Dragon Slayer is that they slay dragons, gaining power by the act itself and/or bathing in its blood. Laxus and Cobra were given lacrimas which allowed them the ability to utilize dragonic elements. The important components for dragonification aren't present for them.