![Yoshi :yoshi: :yoshi:](/styles/default/xenforo/smilies/yoshi.gif)
Ground breaking Yoshi's grab is simple.
There are two ways to do this. The first way, the basic way most characters can ground break most other characters' grabs, can be used
sometimes, but I find that it's a little inconsistent with plenty of other characters and even moreso with Yoshi, mostly because of how he holds them in his mouth. Apparently there are multiple factors for determining ground breaks with most characters, but I have found those factors to be ill-founded and inconsistent across the board, so I don't consider this method when ground breaking Yoshi's grab.
The other method is dependent on how the Yoshi player grabs. The premise is that since you can provide inputs to break out of a grab while the character is actually grabbing you and pulling you to itself (for most characters, this is more or less instant since their arms aren't more than a few feet long; Samus and Link, however, have grabs such that you can actually see the opponent being pulled to them), when Yoshi grabs an opposing player, all that player has to do is button mash enough to get out before the first chew. This is best used with the standing grab because of all the standby frames until the opponent is actually able to be chewed (I believe it's close to a full second). The dash grab is probably the hardest to get out of, and the pivot grab is generally considered (by me) the happy middle between the two.
So, in fewer words, Yoshi attempts to grab an opponent, latches on with his tongue and begins to pull them in. The opponent button mashes as soon as the tongue latches on (the character is considered grabbed at this point) and if enough inputs are provided (while they are being drawn in) by time the character arrives in Yoshi's mouth, they will ground break automagically before Yoshi can get the first chew.