In regards to the addition of stages to the current roster, some additional rules for counter-picking could be put in place to ensure the selection process is a little more fair i.e. the banning of two stages instead of one. However, with only one stage addition coupled with a second ban it would get harder to properly counter-pick in many scenarios, especially if the new stage is one the banner is comfortable playing on. It may potentially be better to leave the striking at one stage alone.
The main contention about Brinstar is it's lava, but there are more factors at work in play.
The effects the lava has on the match include:
- potentially saves stocks by bouncing characters back up instead of dying off the bottom
- leads to extended combos by purposefully tossing people into the lava
- covers portions of the stage which can lead to temporary stalemates
- or advantages for some characters
Additional effects of the stage are:
- extending the platforms out by smashing the tethers tying them to the stage
- creating a small hole in the stage (with ledges) by smashing the eggs
- you can recover through the main platform
- slooooooooooooooooooopes
These offenses aren't so egregious as some may seem to believe, but they aren't ignorable either.
The screen always shakes dramatically before the lava moves so you know when it's coming, even if the timing is randomized. As far as causing stalemates where people sit on one side of the stage, that happens all the time with the fire formation on Pokemon Stadium with it's huge wall. Since the lava will move away far sooner than on Stadium, it's a bit of a moot point.
If the lava ever saves someone's stock enough that they can recover there's no reason you can't just hit them again while they're in hit stun from it.
If you're getting combo'd from the lava it's most likely because you've been spiked or fallen into it. If that's the case your stock was probably saved since that spike likely would have just sent you into the blastzone.
Edge-guarding would be interesting since you can adjust the angle of the platforms to limit your opponent's options for recovery, but with the ability to recover through the stage it could lead to some cool or bizarre interactions.
Jigglypuff would probably benefit the most from this with her ability to just go under the stage and jump up through it. Combined with her up air she could potentially camp under the stage really hard and just poke at you until you cry. Imagine HungryBox at Evo except he has the power to hit you while doing it. You'd have to be pretty tough **** to hit her as she was coming up. A Falco or Marth dair could solve the issue, but not everyone has an answer for this conundrum and even then if she's just buying her time with a stock or percentage lead she's not coming anywhere near you. Jesus Christ, how horrifying.
Falcon and Ganondorf would also see an advantage in being able to grab the opponent from underneath the platform while recovering.
Note: Their recoveries still suck.
For the most part though landing on the stage is a bad idea no matter what since you suffer the landing lag of your up special. Unless you're a spacie in which case you have just basic landing lag. You would be able to hit them anyways though. If they space their recovery so they just barely breach the platform you'll have the time to see where they're going and punish (especially if they're coming from as low as possible in which case they're going straight-up). If they go over they're above you and ripe for punishment.
I think the biggest offender though are the eggs. A Fox or Falco multishine will chew right through them, and if you send the opponent off stage your free to abuse this as you wish. The only thing that comes of it though is stalemate. Even if they respawn really quickly, the ability for a player to potentially halt the match and force a stalemate at will shouldn't exist. I think the eggs alone are a valid deal breaker.
All things considered, I would prefer the return of Mute City if not for it's lack of ledges making recovery all but impossible once off stage. The stage transformations have decent layouts that almost never lead to stalemates or platform camping not possible on other stages and there isn't a walk-off at any point.
The cars are easily less offensive than the lava since when they come by it's usually during transformation sequences and you can retreat to the main platform as it reappears or one of the floating platforms of the transformation.
if you're being juggled by the cars it's most likely because you were hit into them or you messed up.
The ultimate deal breaker is no ledges though, making recovery nigh impossible no matter whom you are.
If I had to pick one to return, I would choose Brinstar if only because the lack of ledges on Mute City is such an offense.
Personally, I would rather them both stay gone.