Noun
one trick pony (plural one trick ponies)
Alternative spelling of one-trick pony
A performing animal (especially a pony) that knows only one trick.
(idiomatic, by extension) A person or group noteworthy for only a single achievement, skill, or characteristic.
Source: en.wiktionary.orgone-trick pony
Have you ever seen a one trick pony in the field so happy and free/ If you've ever seen a one trick pony then you've seen me. Have you ever seen a one legged dog makin' his way down the street? If you've ever seen a one legged dog then you've seen me. Bruce Springsteen
I am fortunate that I get sent scripts and get to meet people I would never have met had I not done 'Harry Potter.' But I feel I had to come out of that show and prove that I am not a one trick pony and can do other stuff. Matthew Lewis
He wrote and starred in 1980's One Trick Pony as Jonah Levin, a journeyman rock and roller. Source: Internet
Unfortunately, Battle Park only makes an appearance in "One Trick Pony," where it's located between Blackthorn City and Mahogany Town. Source: Internet