While the Patriotic Leprechaun is the only FIRST GENERATION pet with Mega Hurry, if it's just the Derby ability you are after I have many, many pets with Mega Hurry. If you're interested we could set up a time and place to meet ingame for a hatch.
FWIW - although Mega Hurry SOUNDS overpowered - +100 is twice as much speed as +50 for Super Hurry - in general it's actually not as good as Super Hurry.
Why? Sure, the speed boost is twice that of Super Hurry, BUT, for one, the cool down time is considerably longer - 50 seconds to only 30 for Super Hurry. That you probably know if you look at the description of the ability. What you DON'T see, and what you might not know, is that the effects of Mega Hurry (the +100 to speed) doesn't last as long as the rest of the hurries. All the other hurries - Hurry, Big Hurry, Super Hurry - last for 15 seconds, but Mega Hurry only lasts 10 seconds.
So, when you do the math, factoring the longer cool down time and shorter duration, Mega Hurry isn't as good overall as Super Hurry. There are some instances it's better - short courses, against a spiffy pet - but I wouldn't be in a hurry to replace Super Hurry with Mega Hurry if I were you.