Marth was one of the better characters in standard Brawl, and the characters who were better than him before (the only two really uncontroversial were MK and Snake, Diddy is going to be widely agreed though) are pretty safe to claim as overall worse. It's not really fair to claim he's bad in BBrawl, and most testers would disagree with that.
As per Pit, most of what you said about him is true, but it kinda misses the bigger picture. Pit's mobility is mostly not so great (he's only really moving fast while gliding, which has its own limits), and Pit's attacks are all around pretty middling in speed which isn't so bad except unlike most characters with that sort of speed of attacks he doesn't have any one that is just really fast. Pit's projectile is good in many ways, but he really can't fire it nearly as quickly as something like Falco laser so it's more of a tool that keeps tagging bad approaches and less of one that fills the screen with hitboxes (it's played more like a Link projectile). His range is also good and mostly disjointed which is nice, but it's not really in the same class as the real big range characters (Meta Knight, Marth, Mr. Game & Watch, Ike, Donkey Kong, King Dedede, etc.). He ends up being pretty middling in a lot of ways which lets him play a really strong fundamentals game and lets him compete with anything, but he doesn't have the same ability to shift matches toward extremes as some other characters have. I suppose it would be strictly more accurate to give him credit for being on the better side of the mid-way point of the cast on most areas, but then you have to consider his generally below average KO options which actually don't really skew his game much just kinda act as a diminished reward on everything else he does since being at, say, 120% against Pit just isn't scary like it is against so many other characters.
Also, about Pit's recovery, the distance is ridiculous, but it's actually pretty easy to catch inexperienced Pits coming back if you use a character with strong off-stage tools (like G&W, Jigglypuff, MK). His jumps are laggy, and his up special is super slow. None of his aerials do an especially good job of keeping him safe. Better Pits will use gliding to be much, much harder to edge-guard, but keeping in mind what you can do against Pit's assorted options is always important.
Angel Ring is a trap that catches a lot of low level players while not being nearly as good as it seems, no offense. It seems really good at first since it's high damage and very high priority, but the problem with that move is that it's really huge commitment. If Pit whiffs it, you can usually hit him with just about whatever you want. Marth is a good example since he can easily just fsmash Pit. The start-up is too bad to be practical to beat projectiles (his shield, on the other hand, is pretty good against certain kinds of projectiles), and since the move can't really be used practically as an aerial move, relying on it ends up forcing you to be really predictable. It still has its uses, but most stronger Pit players use Angel Ring sparingly. If you're against a Pit player who is using it a lot, just focus on baiting whiffs and punishing them.
Most of our testers put Pit in the bottom half of the cast but competitive, though I'll admit BBrawl Pit is one of the relatively unpopular characters so there's somewhat of a larger margin for error here. Since Pit isn't really much of a specialist in anything, most characters just need to play their basic games here. Focus on your character's biggest strengths, which are probably bigger than Pit's biggest strengths, and try to move the momentum of the match away from your biggest weaknesses, which are likewise probably bigger than Pit's biggest weaknesses.
As per those two specific match-ups, for Pit vs Marth as Marth, try to focus on your strong range. If Pit is sticking to the ground, approaching with well spaced fairs will be decently difficult for him to handle as long as you move unpredictably enough to avoid arrows (you are more mobile than Pit so you're geting mindgamed if he's controlling the positioning). Look for big whiffs from Pit both from Angel Ring and fsmash, and punish both with your own sweetspot fsmash. If Pit starts jumping at you, counter with Dolphin Slash which will easily stuff all of his jump-ins but is very unsafe if baited out so be sure to be right when you go for it. If Pit starts being overly cautious and gets scared to throw stuff out, try to wear down his shield and go for Dancing Blades which will put the hurt on him pretty quickly. If the battle comes down to really close ranges, guessing with Dolphin Slash, sitting in shield, and grabbing are really the only things you have, but Pit's options in this domain are hardly great so it's unlikely to come up often. If you find yourself losing with this style of play, it's probably because the Pit is reading your movement and both putting arrows in really annoying places and tagging you with "random" pokes which is hard to really counter, but you basically just need to be less predictable.
As Bowser, it's going to be a slow battle like all Bowser vs strong projectile battles, but it's very winnable with Bowser here. If the Pit is throwing out anything sluggish that you can armor with fsmash, do it since the risk-reward here is really far in Bowser's favor even if fsmash is pretty unsafe to throw out. If you get in semi-close range, ftilt is going to be a good friend here to tag Pit trying to do something he shouldn't from surprisingly large range, and power-shielding arrows that are fired too close is going to be a big key to sneaking in hits. Klaw-hopping used cleverly can be both a great movement option and a great way to tag Pit with a very damaging attack, and it goes to the general philosophy you should have of trying to position yourself so Pit's arrows would be unsafe. If you can ever make Pit want to go on the offense against you, you are in a very strong position as your grab is much stronger than his and Whirling Fortress OoS is the kind of option Pit can only dream of. If you start to slip, don't get reckless, but at the same time, remember that you're a heavyweight who hits really hard so if you are entering exchanges and trading hits, it's almost certainly winning for you. You have to play patiently but at the same time not be afraid of getting hit which sounds contradictory, but it's the same sort of basic play important for all big characters in pretty much all fighting games. Calculated risks that might end up getting you hit are much more the norm than with most of the rest of the cast, and espcially against a character like Pit who will have a very, very hard time scoring KOs on a non-reckless Bowser, you will be amazed at how long you can stretch out stocks.
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Also, while we haven't had much to say lately and have been focusing on some things that aren't really related to this thread, we aren't dead and are still doing some work here. BBrawl3 final is basically going to be BBrawl3 rc with a few very minor tweaks most significantly on Sheik but also hitting a small number of other characters with some issues.
No one in this thread was complaining about Sheik, but in BBrawl3 rc we internally found she could combo jab1, jab2, fully charged Needle Storm which was fairly abusable and mostly beyond the dsmashes, tilts, jab loops, and grabs that we were intending and most people were doing (about half the cast could hold down to aSDI out of it and shield, but it's hard to do on reaction, a horrible DI direction agaisnt any of Sheik's other options, and the other half of the cast couldn't do anything anyway). It turns out that jab2 was actually +17 on Jigglypuff which was... pretty obscene (combo into fsmash possible), and I feel kinda bad letting that slip by without notice. We're cutting that frame advantage back to +3 for jab1 and +7 for jab2 against grounded opponents in a way that makes it universal across the cast which should still be very powerful (+7 on hit off a jab is very good in Brawl) but not the silly things it was doing before and also now normalized across the cast (in the rc, it was way, way better against Jigglypuff than against, say, Fox). For those crunching numbers versus standard Brawl, remember that standard Brawl Sheik jab2 was one of those moves that depended a ton on growth so it comboed only at very narrow percent ranges where it had grown enough to do good hitstun but not so much to knock people away, and in BBrawl now it's a fixed knockback move. The only match-up we anticipate any real negatives to this change in is Sheik vs Luigi since Luigi will slide out of most of Sheik's jab shenanigans now (she can still combo ftilt though). Much less notably on Sheik, we polished up her fsmash a bit so it links better in edge cases. Heavy characters like Bowser no longer drop, and Jigglypuff can no longer wiggle through it.
Speaking of Bowser, we're considering adding a bit of a shenanigan that should make Fire Breath more fun and certainly more useful; Thinkaman assures me this will help him in the Olimar match-up which I'm skeptical of but still this animates shockingly well to the point that I'm kinda loathe to say no. More mysteriousness coming later.
We're looking at how Charizard usmash links too, but that's still a WIP. The easy way to make it link better against grounded opponents makes it worse against opponents above you on platforms; it should be improvable in a reasonable and balanced way, but it's a subtle case that most players will in the end not notice except for being told here. It will have a fairly minor impact on Charizard as a whole for sure, just basically a bit of extra polish.
Overall we're pretty happy with the balance we have at this point and don't think we have strong evidence of significant imbalances so we aren't wanting to introduce major balance changes to BBrawl3 right now (other than a stop-gap on us going a bit too far with Sheik and being happy no one noticed). We were adding some polish in these areas for a maximum quality experience, but we think this is an rc we got mostly right the first time.
Also, I know steeler said something about an Ivysaur dtilt issue, but Thinkaman did some of his typical high quality testing and didn't uncover any issues in regards to this move. Of course for all multi-hit moves there will be ways for them not to link with staleness, victim character, victim damage, and in PT's case fatigue, but by and large, Ivysaur dtilt seems like a good linking multi-hit move.