Amumu is a great tank(love jungling with him) so I want to learn bout how to counter him, is Nunu a good choice?

counter him like you counter everybody else with nunu. just eat his big wraith/ steal as much xp as possible. and if u decide to wait with counterjungling for a while, he's at very low hp at 4:00 mins at the two minigolems, usually a pretty easy first blood. so i would kill him there, and then start conterjungling.

Well, a good Amumu can counter Nunu ^^
While Amumu did my golems I ran to his wraiths and stole both them AND his golems, l0l.

no you mark when his blues are up if youre team wont help steal the first one then it might be hard but amumu with no blue is a VERY bad jungler.

i beleive nunu is the best counterjungler in the game

I know about consuming wraith after my blue, and warding red, but not sure if I should steal his 2 golems or try go gank him while he kills them.

Counter amumu like you counter all junglers

Wards and coordinated ganks on their buffs

Specially second blue / red or first run through at golems

Force 5v5 fight at blue:

1) If the enemies respond, Amumu would either be useless (taking W) right now or later on (taking Q).
2) If they run, take their blue.
3) Ward the entrance to friendly blue. Amumu without blue is Warwick without W.

Amumu is the easiest jungler to counter. Take his Blue at the start and he can't jungle (unless he is a really good player, who would then take E and start from wraiths).

Still, he is a low health jungler which means finding him in the middle of his first run guarantees a kill. Get someone to hide at red and they can just jump and kill him.

Oh, and Nunu is always a good choice.

boots, 1 pot and a ward. Kill him at blue.

Amumu without blue jungles ridiculously slow in the early levels.

amumu is dependant on the blue buff so early in the game

deny him that and hes in trouble