@ Toca
Look here.
Lucario's standing height is 3'11".
Now look at this picture of Mario and Peach.
Now at this pic of Mario and Yoshi.
Looking at the two pictures in sequence or vice versa, you see that Mario is shorter than Peach by at least one or one and a half of his heads. Then looking at Mario on Yoshi, you see that Mario standing side by side with Yoshi would yield him being not too much taller than Mario.
He is probably only two to two and a half-inches taller than Mario.
Now compare Peach to Yoshi, Peach stands taller than Yoshi. Peach is about what the height of a average human female could be in the Mushroom Kingdom.
She is probably around four and a half to five feet tall or bigger by a few inches. Mario is probably around 3 to 3'7" tall by this logic, Which means that Yoshi is most likely anywhere from 3'9" to Lucario's height.
Your size advantage you gave him is therefore
false.
@REL
Funny you mention canines since they can be trained to stand on two legs as part of trick. Lucario could have learned to try and balance himself on two feet on his own if it was the best way for him to fight.
In the absence of this, there are still his "fist-ppikes" he has that he could use to maybe backhand Yoshi in the head with after a lunge. Hell, that one on his chest could be dangerous if all of them are sharpened in some way. With a grinding stone of some type.
No Aura for Lucario, that I am in agreement with...or am I? World History really does come in handy when you have an interesting teacher.
He showed us something having to do with a person's spiritual aura (I did this on my brother and it actually worked! He is many times stronger than I am!).
What you do is have a person put their arms out as if standing like a cross. Then tell them to resist you as you try to push them down. They do so. Now take your hand cut them in half with it all the way down to the feet down the middle.
Tell your subject to put their arms out. Low and behold, they cannot resist you pushing your arms down.
So perhaps Lucario having the ability to disrupt an opponent's spiritual aura isn't as far-fetched as it sounds?
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On a related note, if Yoshi bites done on one of Luc's arms, that spike on the back side of his paw will end up piercing the roof of his mouth, or the bottom of it. Biting down on Lucario's arms at all yields potentially fatal consequences for Yoshi as he would bleed himself by alot if it pierces the roof of his mouth.
Yoshi's large head would be hard for him to maneuver around with, he would probably be having neck pain from having support such a large head on a comparitively small neck.
Sorry, I don't see Yoshi haivng much chance of winning at this point.