Actually, the major issue with the second stock is not Espy abusing it, it was the fact that DEHF was pummeling and the spikes just so happened to form in range. The third stock would have been an auto-kill pretty much if Sonic did an FThrow on him, tech-or-no-tech.
The difference between the Support Ghosts and the Pictochat transformations is simple: The SGs are likely to help you if you are recovering but will almost NEVER kill you (unless you're someone like Ness or Lucas), where as the PictoChat transformations are likely to kill you and almost NEVER help you when you are recovering. Helping the defender is not as detrimental as helping the person doing the offense, ESPECIALLY since, as you mentioned before, the aggressor could simply hover over the pit and finish the "saved" person, as (since they are most likely in a freefall state) will be almost completely defenseless, or at the very least easily pressured. The Pictochat transformations are tedious and can help finish off someone QUICKER than if they were not there, which is why they are worse than Yoshi's Island's dynamic features.
Port Town? Predictable, with the only randomness being the stage landing area, which do NOT have stationary killing points on them. (The cars can be seen in as little as two seconds in advance, and as many as six, plenty of time to get out of the way, which, considering the amount of safe zones on every stopping point, aren't as big of a deal as people make them out to be)
Norfair? The sprays always come at the same speed (andtakes two seconds to reach the stage), the lava walls come in VERY slowly and are nowhere near as lethal as Pictochat's features are.
Green Greens? The blocks are VERY DI'able, if you're hit by a falling bomb block and you're on the outside, you should still survive to 90% (roughly the point where being on the outside would kill you anyway), and if it knocks you toward the center, expect to survive to around 140%. The firewall glitch actually has less knockback, so even if it does occur, it's pretty much just putting a divider on the stage (WHICH can be gotten rid of by destroying all of the blocks on the gltiched side) And if someone doesn't air dodge through the area, they aren't doing it right. The blocks always fall in the same area, so throwing someone toward it is strategic, rather than truly luck. Apples are not a significant threat.
Distant Planet? The only thing the water does is make the "grassy" platforms better for battling than the slope (not to mention that it hinders the little circle camping it had to begin with). Seed Pods take a while to knock down and are very weak if used as soon as they spawn. To the point where most tilts are more likely to kill then they (the "1" seeds) are.
Pirate Ship? The bombs take two seconds to get to the stage AND you get to see the point they launch from VERY easily and way before they arrive. The catapult, rock, little boat, and tornado are virtually as good as fixed considering their beniign natures and large amounts of "startup lag".
Pokemon Stadium(s)? You get to see the transformations on the screen in the back several seconds in advance, and even then, they usually don't adversely affect the match anyway.
Frigate Orpheon? Large amounts of startup lag on the flips (which should NEVER kill you if you play it right)
Brinstar? Lava is the only thing, and you can see it rising in the background too.
Pictochat? Most attacks are longer than the transformation starting and ending sequences.
Also, I can name several characters that could be strongly harmed by thie Picasso transformation, most notably Olimar (can't grab the left side in any way), Marth, Diddy Kong (if he's charging just to the left and below the ledge, he's pretty much screwed), Zero Suit Samus (again, because she can't grab the left side), and the Star Fox characters (ESPECIALLY Wolf).