Pipe Vault
Enter the area and go down the pipe.
Follow the path until you reach two pipes. Jump over the first one with the Piranha Plant and go down the pipe behind it.
In the next area, go down the pipe that is second in line.
Get the coins and then stand in front of where the upper walkway begins. Jump up to reveal a platform you can use to get up.
There is a chest up here at the end of the walkway.
There are also two Hidden Treasure chests just in front of the chest that is out in the open.
Pick up the two Hidden Treasures and then use the springboard to exit.
Now, go down the next pipe and it’ll be time for a mini game.
This mini game will task you with jumping on as many goombas as you can within 30 seconds.
Each normal goomba is 1 point and the golden goomba is worth 3. Scoring 20 pointes will earn you a Flower Tab. Beating your score will earn you a frog coin.
When you’re done, use the springboard to exit.
Go down the last pipe.
Get through the area and go down the green pipe at the end.
Next, make your way to the green pipe by going over the plants.
In the next area, get on the yellow platform and ride it up to get a flower chest.
Get on the next yellow platform and get the coins out of the chest.
Go through the pipe at the end.
You’ll now be at Yo’ster Isle.
There is a Hidden Treasure to the left of the save block.
Get that and then exit the area.
There will be several yoshis in this next area.
Speak to Yoshi and he’ll let you ride him. 
Speak to the red yoshi near the G in “GOAL” to get cookies.
With the cookies, you can challenge Boshi to a race.
You’ll need alternate pressing 
and 
. You’ll get a Yoshi cookie if you can manage to win.
With that done, that’s all there is to see for now here. So go ahead and leave. Head to Moleville.
Moleville
When you arrive, rest at the inn and stock up on any items that you may need from the shop.
When you’re ready, head north toward the mine and you’ll see Bowser.
Enter the mine after the scene.
Jump up on the mole and then jump up onto the next ledge.
Enter the door under the toad.
Jump on the springboard in the next room. Mario will knock himself out and your coins will be stolen from you by Croco.
Follow Croco down the hallway he ran through. Continue following him through the tunnels until you run into one of his minions hiding behind a box. You can fight him or wait here.
I stood next to the box in the path through the area and Croco ran into me. So, you can try waiting for him to run into you.
I stood in the location pictured below.
Otherwise, you can fight his minions as you come across them in the mines until you eventually corner Croco.
Continue damaging him during the fight until he gives you back your items.
After the fight, go through the rooms again until you reach the one with a mole waiting by some rubble. You’ll need to follow the arrow signs in order to reach it.
Speak to the mole and he’ll help you blow open the wall.
Go through the opening and keep going until you’re on the tracks. Head down the tracks until you’re hit by a Shy Guy.
Pick up the frog coin it drops and then climb up the crates to the top floor.
Jump up to get the Super Star from the chest and continue running through the rooms until you come to more crates you can climb.
Climb up the crates. get the chest and then go through the doorway.
Jump over the group of bob-ombs and get the chest next to the save block for a mushroom. Save your game and then grab the flower from the chest by jumping onto and then off of the double stack of crates.
Enter the door when you’re ready.
As you enter the next area, you’ll See Punchinello.
Go around the side of him and walk into him from behind to initiate the fight. If you get him head on, he’ll push you out of the room.
Punchinello
To begin this fight, stick to physical attacks.
When he throws out the mini Bob-ombs, use Mallow’s thunderbolt attack to clear them all out.
Repeat the same process for these. Physical attacks on Punchinello and thunderbolt on the Bob-ombs.
When he calls in the bigger bombs, ignore them and continue to attack Punchinello. If the bigger bombs attack, time your blocks to reduce damage.
When the battle is over, you’ll receive the third Star Piece.
After getting the Star Piece, go through the entrance ahead of you.
You’ll meet Dyna in the next room.
You’ll now be escaping the mines via the minecart mini game.
You’ll need to collect mushrooms and coins while riding the cart. Make sure to brake on the sharp turns to avoid going off the track.
After the cart ride, you’ll be back in town.
With that, Dyna and Mite will be returned home.
Exit the home to see a cutscene. Afterwards, you can explore the town a little more or return to the mine cart mini game to try again.
The shop will have a new toad that will sell different items.
Right now, all he has is a Lucky Jewel. This will give your party health or flowers during fights temporarily. You can return here later for different items.
Go to the house just outside of the mine entrance to buy fireworks for 500 coins. The fireworks are needed to in order to fight a hidden boss later in the game. So, if you don’t buy them now, make sure to come back at some point and pick them up.
If you bought the fireworks now, speak to the mole behind the crates and trade them for the Shiny Stone. The Shiny Stone is a key to a locked door later on in the game.
With all that out of the way, exit town and travel to Booster Pass.
Had kinda hoped that Luigi would be a party member in the remake, he’s in the instruction manual for the og Mario RPG on SNES and in photos from the beta.