You should counter jungle with shaco because of his boxes doing a lot of damage early if you stack them. This champion requires quite a bit of skill so don't get frustrated if you don't do so well the first couple games you play with him. As shaco you should always be looking to gank lanes that are pushed towards your turret, also you should lane gank with his invisibility.

Pros:
Good Escape
Can solo Dragon at 6
Invisibility
Clone can be used at high potential
Cons:
Bad if doesn't get good start
Falls off a little late game
Squishy