WARNING - WARNING - WARNING
NATIONAL LITERACY SERVICE ALERT: A MASSIVE COUNTERPICK ANALYSIS, BASED ON COMPETITIVE EXPERIENCE, HAS BEEN PICKED UP BY RADAR AS HEADING TOWARDS YOUR EYES. FORECAST FOR WORDSTORMS = VERY HIGH. IF YOU ARE ILLITERATE, YOU NEED TO TAKE SHELTER IMMEDIATELY. STAY AWAY FROM YOUR MONITOR, AS WORDS ARE KNOWN TO APPEAR ON IT AND IN THE CASE OF SEVERE WORDSTORMS MAY COVER YOUR ENTIRE SCREEN, POTENTIALLY CAUSING CATASTROPHIC BRAIN DAMAGE.
THESE WORDSTORMS ARE ALSO REPORTED TO BE CAPABLE OF PRODUCING LARGE PARAGRAPHS UP TO 8 SENTENCES IN DIAMETER. THESE LARGE PARAGRAPHS ARE EXTREMELY DANGEROUS, TAKING ENTIRE MINUTES TO READ IN MANY CASES. BE ON THE LOOKOUT FOR WORDS TIGHTLY CLUSTERED TOGETHER; IF YOU COUNT MORE THAN THREE SENTENCES, YOU SHOULD STOP READING IMMEDIATELY AND SEEK LARGE, COLORFUL PICTURES TO HIDE IN.
THIS HAS BEEN A NATIONAL LITERACY SERVICE ALERT.
(EDIT: Upon review, I don't think my response was as large as I thought it was going to be, since I didn't cover neutral stages, and won't. I'm leaving this though because even though I created it, I honestly think the concept is funny as hell. Bully for me and so forth. ^_^;; )
I think you can try Shadow Mosses Island so then Ivy's air ****** would have more use and the walls for Charizard's flamethrower and cornering.
Another stage might be that stage where Palkia/Dialga appear and makes things topsytervy because if people aren't use to Palkia making the place a mirror they can die while you know what to do.
Last idea is picto chat so with the projectiles and stuff it might stop MK from moving freely.
These are all just ideas though not proven =/
2 of the 3 stages you mentioned are banned everywhere you go. >_>;;
PictoChat, on the other hand, seems to make a lot of stage lists despite the hazards it has, and it's actually a pretty good pick for PT against Meta-Knight that I hadn't considered. Ivy and Zard in particular can do a great job of using the stage to their benefit (Ivy's "don't-get-above-me" attacks, Zard's exceptional grab), though Squirtle is about as hampered as Meta-Knight is.
Here's my rundown of good stage alternatives for PT against MK, in order of best to not-so-best:
Final Destination - especially great because you've a 1-in-5 chance of seeing this as your first stage, and can usually counterpick it for a second appearance in the set (at most tournies). Final Destination forces a Meta-Knight to play his usual game without any really unpredictable options. Pass-through platforms are entirely non-existent, and there's plenty of space for all your Pokémon to work with, something each can excel with, whereas Meta can do better in more contained areas. This is the best stage for Squirtle to try and overcome his weaknesses to MK (sorry Elliot, but quick sword swipes = fast DJ hitboxes = don't forget the plural "swipe
s" = difficult approach = tough ******* for Squirtle...shellshifting has to be REALLY GOOD to punish MK like you're talking about).
ONLY NEGATIVE: The_Spamerer, a hardcore Meta-Knight (and Jiggly) player in NJ, consistently banned this one during his matches at Rutgers. Expect similar treatment from other great MKs.
Pokémon Stadium 1 - The things that moved this from "random-neutral" to "counterpick" status at Rutgers are what make this stage another great Meta-Knight counter. There are a number of drop-throughs throughout the stage changes, but that dastardly waterwheel and that large rock-wall (with multiple oddball platforms nearby) are on your side, limiting MK's airgame. The neutral stage only has two drop-throughs spaced decently enough away from each other, and a sufficiently large-enough flat area for you to own him on the ground. Final positive? I'm willing to bet it's an unexpected counterpick against MK, and unlikely to be banned.
ONLY NEGATIVE: That deceptive stage lip hurts you more than him...all your recoveries are more likely to get f'd than his, so be careful when coming back from almost-underneath the floor.
Luigi's Mansion - While the Mansion remains intact, Meta-Knight's air-to-ground combo game has limited height on the first floor, and limited effectiveness on the second floor (due to the roof). Obviously the roof is where he'll fight you best, but you've got one Pokémon who absolutely excels at crushing those above him (her, during the days of Fushigisou..."FUSH!"), and another who possesses a powerful and far-reaching up-tilt/up-smash/up-air combo ('Zard n-airs are surprisingly decent for attacking through platforms, too), so you don't really have to go up there. When the Mansion's gone, you've basically got FD. Great stage for Ivy, especially.
NEGATIVES: Vertical KOs are harder to come by on the ground floor, and Charizard is almost as hampered as Meta-Knight due to not being able to use his jumps to his advantage in those areas.
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Conversely, the following stages are the absolute WORST stages for fighting Meta-Knight. They're similarly ranked, from worst to barely-manageable:
Norfair - Norfair is brutal, since the stage is little more than five large platforms, four of which are drop-throughs with grabbable edges. Shuttle Loops will come at you from EVERYWHERE at high-percents, followed by those high-priority glide attacks. You can deal with the glide, but the initial up+B hit is KO City. All of the platforms are also relatively small, which is good for MK's close-range preference, but the highest two are far apart, which can help you figure out what to do next. The bottom platform, thankfully, is not a drop-through and is one of the better areas for fighting (Ivy's Vine Whip can catch MK off-guard on the middle two platforms). The hazards are neutral here, since your throws offer more positioning leverage for utilizing them than his do...but he can just f-air WoP you into them if you let him. FUN FACT: The Safe Capsule is NOT a Safe Capsule against MK. Just shield the lava wave.
Delfino Square - Delfino Square is also nasty, because it is a close-encounter stage that has three drop-through platforms (too high for Spore Smash, I think) and a floor that can be passed through from below...guess what that means? You guessed it, Shuttle Loop KOs. To be fair, Fly can be similarly used here, but you still have the landing-lag/vulnerable freefall, whereas Meta-Knight will simply glide to safety. Waterfall has enough start-up lag that it can be predicted if used as pass-through attack, and that will get you in trouble, so don't try it unless ledge-hopped for the usual safe return-to-stage. The final suck? The tour-of-Delfino platform stage has small horizontal stage-boundaries, as opposed to the larger ones in some of the other stages. This is definitely in Meta-Knight's favor, since as Elliot stated a moment ago, that's where his kills tend to go.
MINOR POSITIVES: The stage changes are your primary help here, and only half of them. Three of the six stage changes are not in your favor AT ALL (two tower areas: walls; old-school grass-platforms: lack of ground-space), whereas two of the other three briefly but definitely shift the match your way, no matter who you're currently playing as. The two plaza stages offer walk-off edges, which are way more useful for your throws than his, and ample horizontal space to work with overall. The island stage is...
kinda' in his favor, since the slants can make him more difficult to hit or grab on the ground, taking away from your advantage, and although the water would be in your favor for things like Squirtle/Charizard d-airs, odds are Meta-Knight won't land in it. Finally, as an inverse, the vertical ceiling here is relatively low compared to most of Brawl's stages, especially on the grassy-platform area. Use it.
Halberd - This is like Delfino Lite. Same principle during the stage travel due to the pass-up'n'through main platform, but once you get to the Halberd itself, you've actually got a significant advantage, since it's a bigger FD plus minor hazards and one long, central platform. The problem is that the stage is large enough that Meta-Knight can easily just camp away from you and wait 'till take-off again before attacking if he wants. Meta-Knight's defense isn't phenomenal, but he can still easily punish your approach with such a large stage, if you're not careful. This is the stage you'll probably have to deal with if you win the first or second match, since Norfair is OCCASIONALLY auto-banned and you can take care of Delfino yourself at places that allow players one ban a set.
POSTIVE: PLENTY of room for Squirtle to have good shellshifting approaches during on-Halberd segments, helping out his match-up tremendously. Actually dealing damage may still be difficult, but at least taking it shouldn't be as much of an issue.