In my opinion (so nobody shoot meh)
Zoning
Air game - Above average, his air game isn't poor, it isn't bad, depending on what the average is, it could be average. He lacks multiple jumps but with good air speed, potent air attacks and the Egg toss to keep him afloat and hit ranged enemies, Yoshi has a decent arsenal of air moves.
Ground - Average/below average, eh his weakest aspect this could improve with stuff like DR play but that hasn't reached it's full potential and so it's hard to judge, utilizing DR well yoshi can space opponents very well, and certain moves alter his hurtbox, his shield game is terrible however leaving him to try and spotdodge instead, of course this doesn't always work and he will be forced to shield, this could screw him up, so his ground game suffers from this.
Off stage - Above average? (Heh whats the average...), Yoshi can spend some time in the air, he can jump off the stage hit with an N-air, DJ hit with a second N-air and then Egg toss his way back, if your good you can head towards the edge while facing backwards and tossing the egg at the opponent to further this. Yoshi can be somewhat floaty, and he moves through the air horizontally very quickly, When Yoshi mains say he isn't easily gimped they're not lying, if you don't execute a Gimp to perfection, he can likely escape, and it's hard to do that as he has enough mobility to just swerve around you.
He still has some issues though that keep him from being amazing, mostly it's stuff like Ledges, FD's ledge is complete murder, Lylat is no better, this goes for a lot of people but, there are people who can get around those significantly better than Yoshi and so I don't think he should be in there ranking.
Spacing
Extreme long distance - Bearable, he can hold out there with eggs, but he doesn't want too, he wants his opponent close as the eggs are nothing more than a minor convenience at this distance.
Long distance - comfortable, he's at a range where he can dodge things easily without resulting to shielding, his eggs work decently here, and due to his speed if he needs to close in quickly he can.
With his aerial speed regardless of ground or air he can close in or evade.
I wish there was something inbetween bearable and comfortable though....thats where yoshi would be
Medium distance - bearable, dtilt,b-air and ftilt have good range and all are relatively fast, dtilt and ftilt are really whats likely to work however, egg toss works but due to being so close people could sneak through, slow characters can be pushed out and managed, but as not everyone is slow he's not comfortable all the time here..
short distance - comfortable, jabs are quick and his grabs can lead into CG's on certain characters, eggs are pretty much useless here unless they are above you, through dtilt,jab and ftilt yoshi can pretty much get anyone out of his face if he needs to, with utilt yoshi can put them right above him yet not high enough that they're out of his control. back-air and N-air work really well here, especially the N-air which is easy to get your sex kick off at this range.
Egg lay can be used, just with a decent amount of risk, but it's an option, Yoshi has options here, and he would rather be here than mid range against certain characters like Marth and Link.
Killing
Killing potential: Average, Fsmash,Usmash, U-air and F-air can all kill and N-air kills at higher percentages bt really... theres some issues here, for 1 Usmash and F-smash can be pretty insane to get in, U-air is likely the safest 1 here most of the time if you can get it off. N-air is far better for gimping and using it as a killing move means you had to raise their percentage far more then you wanted too... His smashes can hit hard, but they dont hit Hard.
Gimping potential : above average, N-air can easily stop people from coming back, Back air with it's multiple hitboxes and decent range can also deny people but it works best around 115%+ while N-air can be used well at 40%. D-air can screw up some people's recovery, and it can lead into a footstool as well making it very annoying for certain characters when yoshi drags them down and then FSJ's them and they can't recover.
An F-air hit can spell disaster as well whether sweet spotted or not. Egg's also are ranged and can thus prevent people from coming back without Yoshi even leaving the edge.
He can cover a greater range to gimp characters than the norm, but due to recovery, he can only go so far, he's too good to be average, but not enough to be amazing, by not enough I mean he's not Metaknight, if you don't need to be Metaknight to be amazing then Yoshi should be in that slot too then.