For brevity I'm gonna just go into aggressive Yoshi techniques but I want to preface by saying I think yoshi's best tools are his counter attacks, super armor, parry, ECEs, and cc... If mixed up and used properly these techniques will net you a free hit which will almost always be a harder punish than you traded with even if you can only get a nair.
In my opinion aggressive yoshi thrives off of the threat of a mix up. Playing a fast aggressive Yoshi is insanely hard to beat if you can get a sense of when your opponent is trying to hit you. SH fair is an amazing and fast combo starter but commits his whole head and forces you to be facing your opponent on the ground. This position also lends itself to an empty SH towards your opponent and then DJing when they try to SH aerial before your fair hits them. This mix up is used a ton by good Yoshi's, and is applicable on almost any aerial based approach Yoshi has. This mix up is even pretty safe as far as his approaches go since the SH fair doesn't burn DJ and the empty SH into DJ can be a waveland onto any of the platforms assuming your not on FD. Try this with a couple of his SH aerials and I think you'll find good spots to use it on the whole cast. This mix up becomes infinitely deeper when looking at his FH aerials. I won't go too in depth unless you're really curious but lets look at FH bair, one of my favorite approaches. FH instant bair places a hit box above your opponent essentially calling out that they will FH without an instant aerial, it also connects into an up air or nair starting a combo. What if your opponent doesn't jump tho or SH's instead. Yoshi is still in a sick spot since he can then throw a second bair to FF to protect himself coming down, he can DJ into the second bair to change his fall timing, he can turn around DJ fairto threaten the space under the SH bair, he can use DJ to get to a side/top platform, he can fall down with egglay to call out shield, and prolly at least 12 more options I'm not thinking of off the top of my head. I think this is one of the biggest reason people fear Yoshi on platforms. Yes he has fast wavelands and amazing shield drop follow ups, also 0 hit stun on shield, but he just accumulates mix ups on mix ups when he is air born. Since the point of this thread was just to get ideas on approaches I'll list some of my favorites that create interesting opportunities for counter hit mix ups but I hope by my reasoning above you see that looking at approaches is a lot more about positioning than it is about generating a list of good ideas for approaches.
Spacing tools
SH/FH bair
D-tilt
Jab 1
DJC nair
Combo Starters
WD f-tilt
WD-back uptilt(uptilt is just super not safe in neutral imo)
Late up air
Strong 2 hits
Weak nair > D smash
up air > nair
egg > smash attack
My point here is you really can't approach in the same way twice. Yoshi has some solid combo starters on almost every character but they aren't exactly great moves based on the frame data and size in general. If you want to be an aggressive Yoshi you can't be traditionally aggressive especially since using your main mix up tool, DJ, basically can get you killed at 0 if you miss DI on a smash attack coming down. This kinda all ties into what Yoshi's biggest strength is, catching the opponent off guard. Hope this helps, not sure if I answered what you were asking tho... also I've only been playing Yoshi for about 2 years now so I'm still a bit new
