If the measure of how good a game is depends on how much they have Baby Luigi doing the monkey as his idle pose, there's an argument to be made for this being the best game of all time.
For real though I think it's a bit weaker than its predecessor. The Mario fanservice and references have been toned down heavily. I guess there wasn't much new material to work with between the release of that game and this one.
It's the same battle system as before, which I love. Having all enemy attacks able to be either countered or dodged, with specific tells for which bro they're aiming their attack at is such a good mechanic that turns every basic battle into a kind of game in and of itself. And every new location you go to will give new enemies with new moves that you have to try and adapt to as fast as possible to ensure a clean run of the area.
Speaking of the locations, just like Super Star Saga, I really liked the ones in this game. Considering most of the platformer games in this series play it super safe with level themes, this and the last game have had some truly standout scenery for the Mario world.
this game is a lot more linear than the first. While that game was technically linear too, it was an actual full interconnected world and allowed a lot more freedom of the overworld before it blocked you off with a required ability. This game has Peach's castle be the hub while every single quest-area is accessed through portals. Whether intentional or not it is a pretty neat reference to Super Mario 64 if nothing else.
What makes it worse though is how it tricks you with a more open adventure. After the first couple of areas you visit, suddenly a bunch of portals open at once... except you'll quickly find if you enter any of them except the required one, you're immediately blocked off from doing anything before you can even talk to an NPC in that area. They're essentially just setting up exit points back to the castle to those locations for when you reach them via the story. Kind of a tease.
Last time one of my big problems was how the game tried to shove way too many field commands into A and B at once, resulting in way too much micro managing of your skills which constantly led to accidently using the wrong thing, or scrolling past the 1 of 4 sets of skills you can have on screen. This game kind of fixes that while introducing a new problem. See, with the DS having 2 extra buttons it'd make sense to have A and B always be jump, and X and Y be one of the bros special moves, able to switch just those with R like before. But with the introduction of the babies they take ownership of these new buttons (remember how in SSS every single Mario action was A and every Luigi one was B? That was kept, so the babies are now X and Y). They do at least give the babies their own actions, so it's spread out across the four face buttons. In fact they even trim the command list by removing the elemental attributes from Mario and Luigi, leaving all 4 characters with exactly 1 special skill and their basic jump commands. Works out pretty well - except the babies are by default always riding on the older versions back, so every time you want to use any skill you need to throw them off. You wanna use Luigi's spin move? Well first you need to press X or Y to throw the babies, which will automatically transfer control to them, so then you need to press A or B to put it back to adult Mario & Luigi, then press R to switch from jump commands to special commands, and now you can use the spin. It's just annoying they added this extra step when the babies show they are perfectly capable of moving around the world by themselves. I think the game would be a lot smoother if they just had a 4-person train, only needing to give piggyback rides to the babies to get up higher jumps.
This also applies for battles. Why are the babies relegated to sitting on their partners back when they show multiple times they're more than able to fight by themselves? Their stats outside of power and stache (luck) don't even apply in most non-baby-only battle unless the older bro faints, leaving the baby to step in as an extra life. However I do kind of get this one, as only the babies have hammers now, so it might be hard to think up ways for enemies whose moves can be countered with hammers to not be unfair on the older counterparts who don't have them.
My least favourite change of the game is the swap between bros moves to bros items though. In terms of them being a limited resource that's actually completely fine. The game gives you more than enough of every item without you ever even needing to buy them, which itself is always an option. I also even like actually using them, as each one is essentially it's own mini-game, and the extra buttons can often be used in smart ways, such as the shell items which normally have Mario and Luigi kicking them back and forth between it hitting an enemy. A simple concept, but a baby rides the shell and if you press the babies button when the shell hits the enemy it deals extra damage. I like the idea idea.
But they're just so horribly balanced. On one hand you get some items which are better versions than older ones, like red shells that do more damage than green shells, while also not stopping if they defeat one enemy, and start attacking the next one. These are fine. They do make the first item redundant, but as a concept having an "upgrade" version of an item is fine.
To demonstrate this, let's look at 4 (out of only 10 total) items.
Firstly there's the Cannonballer. It shoots all 4 characters into the sky at one enemy and they all fall onto the enemy in a random order - press their corresponding button as they land and deal big damage. Nice and simple.
Then there's the direct upgrade from this - the trampoline. It does more or less the same thing, except it targets all enemies (a random one is chosen each time a character drops) and it goes on forever, progressively getting faster, until you miss a button input.
All well and good! Then there's the Chain Chomp item which actually comes between these 2. It's another "lasts forever and gets faster until you miss an input". In it the adults will run across the screen one at a time being chased by a Chain Chomp, while the baby rides on the back of the chomp by the tail. Press the adult brothers button to jump on the enemy, and press the babies to swing a hammer for a bit of extra damage. It's a fine concept but a bit redundant isn't it? It's just doing more basic jump damage. It can't really do anything that the trampoline can't do, even with the fact the babies use hammers because if you use it on a spiked enemy the first jump will fail and the move will end.
Then there's the copy flower which you get AFTER the trampoline. In it all the bros, adult and baby, create an infinite amount of copies of themselves and it's yet another "jump on an enemy until you miss a prompt". But while the trampoline has one character falling from the top screen at a time, this move has multiple of the characters running from left to right, making it much harder to keep track of AND the damage even seems to be less per hit. So what's the point? Why would I ever use the copy flower which just has me jumping on the enemy in a much harder to track pattern than the trampoline which also just has me jumping on the enemy, in a much easier to follow pattern? And if you miss a prompt for the copy flower it insta-ends the move, while if you do for the trampoline it let's you still attack with the remaining 3 brothers as they fall down. So why is this one of the last items you unlock? It's so stupid and I want answers!
Ok other than that it's a great game.
For real though I think it's a bit weaker than its predecessor. The Mario fanservice and references have been toned down heavily. I guess there wasn't much new material to work with between the release of that game and this one.
It's the same battle system as before, which I love. Having all enemy attacks able to be either countered or dodged, with specific tells for which bro they're aiming their attack at is such a good mechanic that turns every basic battle into a kind of game in and of itself. And every new location you go to will give new enemies with new moves that you have to try and adapt to as fast as possible to ensure a clean run of the area.
Speaking of the locations, just like Super Star Saga, I really liked the ones in this game. Considering most of the platformer games in this series play it super safe with level themes, this and the last game have had some truly standout scenery for the Mario world.
this game is a lot more linear than the first. While that game was technically linear too, it was an actual full interconnected world and allowed a lot more freedom of the overworld before it blocked you off with a required ability. This game has Peach's castle be the hub while every single quest-area is accessed through portals. Whether intentional or not it is a pretty neat reference to Super Mario 64 if nothing else.
What makes it worse though is how it tricks you with a more open adventure. After the first couple of areas you visit, suddenly a bunch of portals open at once... except you'll quickly find if you enter any of them except the required one, you're immediately blocked off from doing anything before you can even talk to an NPC in that area. They're essentially just setting up exit points back to the castle to those locations for when you reach them via the story. Kind of a tease.
Last time one of my big problems was how the game tried to shove way too many field commands into A and B at once, resulting in way too much micro managing of your skills which constantly led to accidently using the wrong thing, or scrolling past the 1 of 4 sets of skills you can have on screen. This game kind of fixes that while introducing a new problem. See, with the DS having 2 extra buttons it'd make sense to have A and B always be jump, and X and Y be one of the bros special moves, able to switch just those with R like before. But with the introduction of the babies they take ownership of these new buttons (remember how in SSS every single Mario action was A and every Luigi one was B? That was kept, so the babies are now X and Y). They do at least give the babies their own actions, so it's spread out across the four face buttons. In fact they even trim the command list by removing the elemental attributes from Mario and Luigi, leaving all 4 characters with exactly 1 special skill and their basic jump commands. Works out pretty well - except the babies are by default always riding on the older versions back, so every time you want to use any skill you need to throw them off. You wanna use Luigi's spin move? Well first you need to press X or Y to throw the babies, which will automatically transfer control to them, so then you need to press A or B to put it back to adult Mario & Luigi, then press R to switch from jump commands to special commands, and now you can use the spin. It's just annoying they added this extra step when the babies show they are perfectly capable of moving around the world by themselves. I think the game would be a lot smoother if they just had a 4-person train, only needing to give piggyback rides to the babies to get up higher jumps.
This also applies for battles. Why are the babies relegated to sitting on their partners back when they show multiple times they're more than able to fight by themselves? Their stats outside of power and stache (luck) don't even apply in most non-baby-only battle unless the older bro faints, leaving the baby to step in as an extra life. However I do kind of get this one, as only the babies have hammers now, so it might be hard to think up ways for enemies whose moves can be countered with hammers to not be unfair on the older counterparts who don't have them.
My least favourite change of the game is the swap between bros moves to bros items though. In terms of them being a limited resource that's actually completely fine. The game gives you more than enough of every item without you ever even needing to buy them, which itself is always an option. I also even like actually using them, as each one is essentially it's own mini-game, and the extra buttons can often be used in smart ways, such as the shell items which normally have Mario and Luigi kicking them back and forth between it hitting an enemy. A simple concept, but a baby rides the shell and if you press the babies button when the shell hits the enemy it deals extra damage. I like the idea idea.
But they're just so horribly balanced. On one hand you get some items which are better versions than older ones, like red shells that do more damage than green shells, while also not stopping if they defeat one enemy, and start attacking the next one. These are fine. They do make the first item redundant, but as a concept having an "upgrade" version of an item is fine.
To demonstrate this, let's look at 4 (out of only 10 total) items.
Firstly there's the Cannonballer. It shoots all 4 characters into the sky at one enemy and they all fall onto the enemy in a random order - press their corresponding button as they land and deal big damage. Nice and simple.
Then there's the direct upgrade from this - the trampoline. It does more or less the same thing, except it targets all enemies (a random one is chosen each time a character drops) and it goes on forever, progressively getting faster, until you miss a button input.
All well and good! Then there's the Chain Chomp item which actually comes between these 2. It's another "lasts forever and gets faster until you miss an input". In it the adults will run across the screen one at a time being chased by a Chain Chomp, while the baby rides on the back of the chomp by the tail. Press the adult brothers button to jump on the enemy, and press the babies to swing a hammer for a bit of extra damage. It's a fine concept but a bit redundant isn't it? It's just doing more basic jump damage. It can't really do anything that the trampoline can't do, even with the fact the babies use hammers because if you use it on a spiked enemy the first jump will fail and the move will end.
Then there's the copy flower which you get AFTER the trampoline. In it all the bros, adult and baby, create an infinite amount of copies of themselves and it's yet another "jump on an enemy until you miss a prompt". But while the trampoline has one character falling from the top screen at a time, this move has multiple of the characters running from left to right, making it much harder to keep track of AND the damage even seems to be less per hit. So what's the point? Why would I ever use the copy flower which just has me jumping on the enemy in a much harder to track pattern than the trampoline which also just has me jumping on the enemy, in a much easier to follow pattern? And if you miss a prompt for the copy flower it insta-ends the move, while if you do for the trampoline it let's you still attack with the remaining 3 brothers as they fall down. So why is this one of the last items you unlock? It's so stupid and I want answers!
Ok other than that it's a great game.