I thought about CPing D3 to Brinstar. Have any thoughts on that since he won't be able to CG far?
Personally, if I want to CP D3 just to get rid of his grab, why not head to Norfair or even just a small stage or stage with platforms. All of them will do the trick, as well as keep your advantage of ETS and the pivot grab.
Well here is my opinion on the whole best CP for yoshi or any character
I don't think there is a right or wrong answer/opinion on what is the best CP it all depends on your style of play and whether or not you like the stage if you like non proportional weird small stages then go ahead and pick brinstar if you think it will work but if you rather play on a more even balanced neutral stage then pick a neutral stage it all matters on your style of play and what style of stage you prefer.
The thing is we aren't discussing so much opinion as we are fact. When you look at counterpicks, you want to either have it as your advantage, their disadvantage, or a combination of the two. When naturally looking at Yoshi's abilities, Brinstar severely limits his options. He can barely space with pivot grabs, he has lost his CG, and he can't ETS from the edge. There are other stages that would give you the same perks as Brinstar, but without all the negatives so in this instance, why even choose it?
If you want to talk about CP theory then we can do that as well. To me, there are three different types of players: those who beat you, those who go even with you, and those you beat. (This will also take into account instances where they choose characters that CP you like G&W. Obviously if yall are on equal skill, but he has G&W, by theory, he should win when given neutral conditions.)
If you are playing someone you beat, then odds are you don't really want to go to a CP stage. You can easily outclass them on a neutral like FD, BF, or SV. There is no point in possibly throwing out more random events that could cost you the game when you know solely by skill and character choice, you can beat them.
If you are playing someone you go even with, then you have two options. You can either go for a neutral and hope that you come out victorious or choose a CP that gives you better options than your opponent. In this case, once again, you won't want random things to occur. Just something to give you an edge like Delfino or Halberd.
If you are playing someone who beats you, then you have to rely on another two options. Either you CP a stage that gives you better options so that yall become even in terms of winning, or you really on the random effects to win. In the latter, you CP stages such as Norfair or pictochat in order to possibly level the playing field by knowing the stage more than your opponent or hoping a random effect gives you a severe advantage for that time.
This is my view on CPing. Of course this doesnt account for every instance, but in general, this is what I think about when I CP opponents.