To Specialize or not to Specialize

one-trick pony
一つしか才能のない人

Example:
That boss is a one-trick pony. Just avoid its fire breath and you can't lose.
あのボスキャラは1つの攻撃しかないよ。あの火吐きを避けたら、負けられへん。

Comment:
This word has a negative image, I think. Also, no good translation for this showed up on ALC. Is there any Japanese expression for someone who is only good at one thing?

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jack of all trades, master of none
多芸は無芸。

Example:
You can't beat experts if you're just a jack of all trades, master of none.
多芸でも無芸ならエキスパートより勝てないで。

Comment:
It's sort of hard to translate since the Japanese is a saying, but the English is a noun that describes someone. Just "jack of all trades" probably has a positive image, but if you add master of none, then it becomes negative.



I guess I strive to be a master of all trades (except art...).