Personally the worst wyvern in the game for pve in my opinion is lightning bc their breath attack is an enormous threat to you and your tames and there isn’t room for mistakes, they are the best for pvp however due to them doing so much damage. They are definitely for more experienced players tho. Poison is ok. Their breath attack is nearly impossible to aim while flying but does good damage and basically shreds players. In pve they are helpful in ground but overal probably the worst wyvern. Fire are overall the best. Great for pve and pretty solid for pvp. Ice is pretty bad for pvp but arguably best for pvp bc of its high stamina and weight making good for farming.