Which champ?

I personally like J4 even though he is barely average on both roles (he doesn't excel at much) however if you are good with mana management he tends to do a tad better on top because of his early game damage.

Wukong is a tad more complicated, I would't recommend him to jungle unless you have some mileage as jungler. He comes with a lot of problems early game as his clear speed and sustain is really poor; also his gank potential is limited due to the lack of CC(he has a lot of brust damage thou) his ganks will be similar to shy as you will have to dash to the opponent and try to deal as much damage as possible before they shelter on turret, your kit is better than shy thou as you have a point and click dash and a stealth. Post 6 your ganks gets much better if your ult is up but the cd is considerably high. On top he does ok, he can harass and bully without problems and his decoy will reduce most of the retaliation. Again you have no build in sustain so you depend on your decoy quite heavily on trades.

Nocture is a good assassin jungler. As any assasin he needs early kills in order to be effective so playing him is a gamble. Unlike many other assassin junglers thou his kit lets him farm quite easily so clearing is not an issue. if for any reason your team is playing aggresive and there is no opportunity to gank you can always play him as a farm jungler (udyr style) and become a ridiculous split pusher late game. I don't play him top so I can't tell you about his laning phase but late game will be similar to a tryndamere, if you get fed you stick with them and kills the carries, if not just splitpush and kill anything that comes towards you.