He's really a Jungl-gnar
Top shomp, Gnar looks like he'd be an interesting jungler.
With feral flare.
Because the roof is on fire and he don't need no mana.
His kit makes it look like he'd be a great ganker in big form. Sure he could top, but why waste all that CC he's got? Q - a slow W - the passive will help his clear and the big active is a stun E - gap closer, a slow in big form R - helps his movement speed bonus on his W (stickiness) or gives him a nice AoE CC in big form.