Before I start, I'd like to note that all I'm about to say is simply on the basis of proper stage analysis. I have no intention of getting into an argument with anyone over
my opinion. Any arguments over what I'm about to post should be
indirectly stated, not told to me. I have don't have the final say in determining stage legality, so any arguments voiced directly at me are
pointless.
My full argument for Port Town: Aero Dive's legality as a counterpick:
(Reminder, IMO if issues that are addressed are deemed as strategically important or have very little influence on competitive play, I deem them meaningless)
Reasons PT:AD works as a counterpick:
1. The stage is constantly changing (like PS1, a neutral) at a predictable pace.
2. The hazards are both predictable and avoidable (trust me, I've read the stage analysis, EVERY PART of the stage has a way to avoid hazards)
3. There are no ledges most of the time (Discourages edge camping and planking. This should be kept in mind for counterpicking characters or players (looking at you Sharky

).
4. The blastzones vary in both width and length (Rewards knowledge of the stage itself)
Port Town is an agreeable stage as a counterpick. Like most counterpicks, knowledge of the stage itself can either make or break you (this is true for all stages, including neutrals). All three of the points I've mentioned are viable strategies for any player. They can all be learned, analyzed, and used to the advantage of the player who picked it (If the opponent has taken the time to learn the stage, the opponent may use these to his advantage as well).
Scenario 1: Yoshi's Island (Brawl), a neutral
Player1: Has knowledge of all neutrals
Player2: Knows FD like the back of his hand, but the rest he's clueless
Yoshi's Island has a very unique "hazard" that saves the player rather than hurting him. The support ghost (known around here as "Percival the Prejudiced", or "Percy" for short) always pops up in the exact same area on the left side, and the exact same area on the right side. P1, the seasoned player that he is, knows Percy very well. P2, on the other hand, does not and lo and behold, P1 smashes P2 off the stage. P2 attempts to recover, narrowly misses the ledge, then hugs the stage wall all the way down.
In the same situation, the roles are reversed. P2 smashes P1 off the stage. P1 attempts to recover, narrowly misses the ledge, then glides slowly in his helpless state towards the predictable point of Percy's arrival. Percy saves P1's precious stock just in time.
I'll admit, this situation is a bit idealized, but it has nonetheless happened several times, and players who don't know the stage often lose this benefit (As a matter of fact, the cars are easier to predict than Percy's arrival is). The same is true for the cars on Port Town. Knowing which parts of the stage cars would appear, where to be to dodge them, and which stages of transformation were completely safe was intensely useful in my match with JamesG (even though I was killed by the cars, not James, my stage knowledge got me the win anyway as I knew the patterns of the cars and never had to worry about them).
EXTREMELY IMPORTANT FINAL NOTE
A few of the stages of transformation make the cars noticeable before they run through, while the other stages are random. If anyone saw me play last night during the stages of transformation where the cars weren't predictable, I hung around the far edges of the stage (the safe spots) and camped a bit. This momentarily change in my gameplay was by choice, just as some characters "time out" certain Delfino transformations. This knowledge of the game made my win MUCH easier to obtain.
There was also another part of the tourney where 13370 was completely stunned by getting his stock taken away, saying he thought that he was in a safe position. And 13370 has been practicing on that stage for a while now.
Wanting Port Town legal is no different than wanting Mario Kart Race Track legal in my eyes.
Over the week I mentioned I practiced on Port Town: Aero Dive, I practiced a combined total of 33 MINUTES, read up on the stage's hazards, and fully understood everything I would need to do to make the stage work in my favor. Just 33 minutes guys, IMO this stage is not very complicated at all.
"Having trouble trumping your opponent's stage picks? Can't find a counterpick that works for you? Try Port Town: Aero Dive. Better CP results in just 33 minutes or your money back"
Also, I had an extremely good feeling that the cars were going to hit me when they did. However, I stood there anyway as I wanted to test the spot for later. As a rule of thumb about me, never judge what I'm thinking based on what I'm saying. If everyone did that, we'd assume Cura's head was empty while he's playing 'cuz he doesn't say a thing and that's likely not the case. I was completely ready for the cars to hit me, it was the force that I wasn't prepared for (I have no doubt, though, that if I'd put in 7 extra minutes of practice I wouldn't have died because of it).
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My full argument on Yoshi's Island (Melee) as a counterpick
This one will be much shorter, as I'm quite sure several smashers (Cura, Sharky, Frost) already find my argument viable.
Reasons Yoshi's Island (M) works as a counterpick
1. The stage heavily rewards proper DI and Techs
2. The primary hazards (The blocks) can be removed for short periods by either player and have strategic value when both absent and present (As in point #1)
3. Grab releases are both hindered and helped (Yoshi gets a walkoff infinite on Ness on the hill, and certain characters must not pummel and throw immediately on the pipe or the grab is instantly broken)
4. Advanced knowledge of the stage can always prevent death by certain moves (EX:Olimar's U-throw with Purple pikmin always fails if used while standing on top of blocks)
Misconception:
The ceiling is not low. In fact, it's deceptively high.
I believe why JG is arguing this is because of my B-throw kills. For the record, James died off the SIDE every time I killed him with B-throw, NOT the top.
Scenario #2: Yoshi's Island (M)
13370: Olimar
Sharky: Olimar
During heated combat, Sharky grabs my olimar and U-throws him underneath the blocks. I react to this by teching the block. Sharky, however, follows up on this by U-smashing me while I was still in the Tech animation.
After this, Sharky says, "Wow, that time the tech worked against you"
The reason I mention this is because Teching every move doesn't bring salvation on this stage. Yoshi's Island (M) encourages SKILLFUL techs, not random/reaction ones. Stages that give mediocre players extreme random advantages are on grounds for ban, not stages that reward people who know precisely when and when not to apply advanced techniques. If I had bounced off the block then tech rolled the ground afterwards I would have avoided the U-smash.
If people can say "Don't get grabbed" is a completely legitimate playstyle (And I believe it is, I encourage the use of all grab releases/CGs if the victim screws up and falls into them), then "Don't fail the tech" doesn't seem too farfetched as a strategy either.
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(This note has been removed upon reading previous statments)
These are my true thoughts about these stages. As much as I was joking around last night about them being gay win-tickets for me, I truly believe they are viable counterpicks (And as Cura proved, knowledge of the stage isn't all you need. He solidly beat me even though I was more experienced with the stage).