I've been fortunate enough to play nearly ALL the top PT mains: Reflex, Magic, typh, T-block, and MaTa. Out of those, I've only used Bowser against typh, T-block, and MaTa. I still mained PT when I played Magik and Reflex well over a year ago.
It's crucial to remember how fatigue works, mainly for the Squirtle MU: When a Pokemon comes out, they have 90 seconds worth of freshness. Every second they're outside of their Pokeball, one second is taken off that freshness, and every MOVE used outside of the Pokeball removes an additional second. This means Squirtle gets fatigued MUCH faster than Charizard, for example. For every second a Pokemon is within a Pokeball, he recovers either 2 or 3 seconds (I can't remember) of freshness.
The hardest part about this MU is readjusting to each Pokemon's playstyle because they all require Bowser to play differently. I'll break it down into all 3 Pokemon.
Squirtle's gonna rush you. If for some reason Squirtle starts camping you, know you've already won the fight: A camping Squirtle makes for a fatigued Squirtle.
Following that mentality, don't be overly aggressive against Squirtle. The more you wait, the weaker he gets.
Squirtle's main approach method is aerials, most notably his fair and bair. Bairs are often used following a shellshift and are often retreated, making bair harder to punish. Fair, on the other hand, isn't hard to shield and punish as long as you're used to how fast it comes out. Squirtle's nair is much rarer. At low percents, he's likely to SH nair into a grab or jab. If you see Squirtle SH nairing, get ready to shield the jab. If you can shield jab 2, you can grab Squirtle, which is where Bowser really shines in this MU. The AR CG is really, really easy on Squirtle--just dash grab him right before he hits the ground (exact same timing for GR>Klaw on him). KOing Squirtle is easy GR-wise compared to the rest of the cast and really, really, REALLY satisfying: We have GR>runoff upair on Squirtle. If Squirtle's around 80-100%, DO IT.
Squirtle will NEVER SH upair because it has ending lag. If you happen to see Squirtle do that, punish him. Likewise you'll almost never see SH dair. Dair's mainly used FH'd atop your shield because it shieldpokes OR offstage because it has pretty good knockback and helps make fair/bair more fresh.
At low percents, Squirtle has an uptilt>upair>fair combo for something like 60% damage. It's basically a bunch of uptilts, a few upairs, and then a fair. I honestly don't care. Bowser gets back in the game really easily in this MU as long as you get back to the ground after the fair.
When Bowser's around 130ish%, Squirtle can KO with dthrow. If you notice Squirtle playing extra aggressive, he's probably fishing for a grab. HOWEVER, if Squirtle is fatigued (if Squirtle stops moving and bends over, it means he's tired), this move KOs MUCH later. Just DI it up and into the corner.
If Squirtle does a ridiculously long grab on you that covers half the stage out of his shellshift and successfully grabs you on the ledge, DO NOT BREAK OUT. This is Squirtle's Hydrograb. If you mash out, you will be automatically placed underneath the ledge in a PERFECT position to be footstooled. If you don't mash out, you will not be released in that position.
Squirtle's ftilt is really safe on shield. It comes out SUPER fast and has hardly any lag whatsoever. At low percents, you'll likely see Squirtle going for ftilt>jab if he decides to approach you on the ground. Another trick Squirtle likes to do when you're offstage is wait for you to come to the ledge, ftilt you, then runoff fair.
Bowser does much better against Squirtle on a stage with little to no platforms OR where the terrain is uneven, like Brinstar (Bowser takes a massive dump on PT there). Uneven terrain messes up Squirtle's shellshifting, which gives him one less mixup tool in approaching Bowser, which is REALLY important for Squirtle in this MU.
If you have a lead against Squirtle, especially a stock lead, DO NOT APPROACH. Squirtle has NO safe way to approach Bowser as long as you're aware of how his movements function.
Ivysaur's gonna be going for a lot of Bullet Seed here. Most PT mains say BS is overrated, and it totally is...with the exception of tremendously fat characters like Bowser. I don't remember the exact percents because this is a MU I don't pay attention to my percent in, but I think it's around 30-45% or so. Don't care. At low percents you should expect nair>BS. Nair's punishable by Fortress OoS, but be aware that it does shieldpoke.
Bair comes out really fast but it stupid weak. As in like a measly TWO PERCENT stale/fatigued. It has hardly any lag, though, so it can be shorthopped into other attacks pretty easily.
Dair/upair are both REALLY laggy. Expect upair when Ivysaur is on a platform above you. Ivysaur like to use dropdown upair just like Wario. However, unlike Wario, it not nearly as lagless. If you see it coming, you can punish the ending lag really easily. Dair can spike, but you'll most likely see Ivysaur go for a nair spike over a dair spike when tether edgeguarding because nair has a LOT less lag and makes it way easier for Ivysaur to regrab the ledge.
Fair's often done retreating and can be harder to punish when executed properly. It's one of the ways Ivysaur will KO.
Unlike Olimar, Ivysaur goes up a BIT following the tether, but it's not much. Ivysaur's not as lolivysauroffstage as you'd think, though. If you're grabbing the ledge and Ivysaur is facing you, he will either Razor Leaf you (which has random trajectory and may actually miss, therefore BONING Ivysaur's hopes and dreams FOREVER), nair you, or fair you. Ivysaur also like to use REVERSE Razor Leaf in order to bair you while you're on the ledge. If you see Ivysaur's back to you offstage, this is the ONLY thing he'll do. One more thing of note is if Ivysaur has no chance in hell of making it back, he'll still go for the Vine Whip. If he sweetspots YOU, you'll be sent flying downwards along with Ivysaur. It's deceptively strong, and a lot of people forget about it.
That said, you want Ivysaur offstage ASAP. This is a MU where I GR>dtilt even if it's not gonna KO just because it has the most knockback out of our GRs on Ivysaur and thus sends him closer to offstage. We can infinite Ivysaur via GR if he doesn't mash jump, which you'd be surprised how often you can pull off on PT players. Like Wario mains, they're used to NOT mashing jump to escape grabs because Squirtle gets additional GRs against some characters if he mashes out jump, ie Fox can GR>upsmash. I find that after like 4 regrabs or so, the Ivysaur will often mash jump as a means to try escaping. Most of the time I just go for GR>dtilt, though. If Ivysaur's around mid percents, one fair/nair/bair offstage will send him too far away to recover.
If you see Ivysaur throwing out Razor Leaf, don't worry. It's one of the easiest projectiles to PS in the entire game. A good Ivysaur, though, doesn't use RL to damage you. Like Samus using Missiles to bait a shield and get a grab, Ivysaur uses RL to bait shields. Some Ivysaur also like using runoff RL when you're knocked offstage just for extra damage before they grab the ledge and then proceed to bair/nair edgeguard you.
Ivysaur's fsmash can be angled and is deceptively strong and fast. If you can shield it, it's punishable. Dsmash is lol and won't EVER be used unless you're getting HARD trolled. Upsmash is stupid, stupid strong and will KO Bowser MUCH lower than we're used to, but it's craaaazy laggy. Most Ivysaur tend to upsmash in the opposite direction you think they'd upsmash. It's something typh told the PT boards a long time ago, and a lot of them I played still do this.
Ftilt can shieldpoke and is used to rack up damage. At low percents, expect bair>reverse ftilt. Dtilt is kinda like ICs' dtilt in that it comes out fast and can actually KO. If Ivysaur rolls behind you, expect a dtilt (or BS because PT mains can just go beat off right quick as Bowser gets BS'd). It's a trick Reflex told the PT boards to do against big characters like D3 and DK to get behind some of their long-reaching attacks like ftilt (moreso for D3 than DK in this example, of course).
Beware of Vine Whip as a KO move. People forget Ivysaur can do it onstage. Like Olimar's chain, it comes out diagonally. It has SUPER STUPID knockback when sweetspotted. If you're diagonally in the air away from Ivysaur and he's onstage, you're either gonna get Vine Whipped or he'll read your AD with upsmash or a grab/pivot grab.
Get ready for Rock Smash and grabs. This is a MU where you don't wanna be caught shield camping because RS can shield poke if your shield isn't full/almost full, and Charizard has the greatest grab range in the game (I forget if it's dash grab or standing grab range--I know D3 is one, and Charizard is the other. Regardless, watch your shield.).
Ftilt beats out RS with proper spacing and timing. Time it too late, and you'll take damage as well from the smaller bits of RS. Time it right, and the rock will drop straight down and do no damage or knockback. At low percents, Charizard will go for RS>upsmash. It does like 45% damage or so.
One good thing about RS is Charizards tend to use it waaaaay too much instead of trying to go for more creative approaches. When in doubt, they usually just Rock Smash. If you're used to its range, you can bait it.
Charizards also like doing falling Flamethrower on me. If I see them doing it more than once, I usually bait it and then Bowser Bomb Charizard. It works really, really well. I land more Bowser Bombs on Charizard than any other character in the game just by baiting Flamethrower and Rock Smash.
Nair is relatively lagless when SH'd. Charizard have been using this a lot the past year or so as part of their expanding his metagame. If Charizard nairs in front of you, he's baiting you into a grab. It's laggy when FH'd, though.
Bair is strong when sweetspotted and comes out fast. If you pressure Charizard up close, though, it's really weak. Note that it can spike when you're up close to Charizard's body. It's a very weak spike, but people rarely expect to get spiked by that move in the first place.
The big aerials to watch out for are dair and fair, most notably offstage. This MU's pretty even just by baiting Charizard and then punishing him as long as you don't get hit by dair or fair offstage. Both of them gimp at really early percents.
I go back and forth on which character we do best against. It's honestly player and stage dependent. They all have ways to beat Bowser, but it's nothing staggering. I'm 100% confident in my -1 rating and refuse to accept PT as a -2, which is what the PTs are pushing for for some reason. I've played this a MU a LOT against the BEST players, and while they definitely beat us, it's an easily winnable MU.
Oh, and if you ever play a PT, take his *** to Brinstar. Back in the day some dumb PT main posted that Brinstar was really good for PT, so some of them still like it, but the truth is PT is garbs there and Bowser is awesome there.
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