There isn't all that much that is intimidating about the Dolphins, unless you're a shark. Luckily at least one of these designs somehow makes the dolphin look intimidating. The bottom right features a larger dolphin figure, which might be the best design out of all of them. The top right gives me a little too much of Bronco vibes due to the deep orange. The bottom right looks a lot like the original helmet, except with some added frills like wavy color lines.
The Dolphins hold a great place in my heart because of their inclusion in the film, Ace Ventura, Pet Detective. It was the Dolphin's mascot who was kidnapped. I won't spoil it for you, but the movie has a climactic reveal of who kidnapped the Dolphin, but it's not for the faint of heart.