When it comes to a Mario timeline, there's no certainty. There's multiple concepts for singular events, including games that haven't appeared over here and the switching of character names. We will take time to go over just a few of these mix-ups.
First, let it be clear that Nintendo isn't stupid for doing this; this is Miyamoto's wish. He doesn't want a singular plotline so that Mario's posisions in games are limitless.

Case 1: Who is Donkey Kong?
Many believe that DK shouldn't be in Mario games, but instead in his own. Some follow what the original DKCountry says and take him for Mario's old nemesis' (the old school DK) son. This opens up yet more theories that Mario is the original Mario's son because how could the old school DK be old and he not? Deeper observed, one would say Baby Mario is today's Mario. That's why he's in Mario Golf and Mario Tennis(64) along with another Mario. But then why aren't Peach, Daisy, Yoshi, Toad, and Bowser young? As you can see, a Mario fan can get very confused this way.
Case Unsolved

Case 2: Is Wario a Mario brother?
Some say he is, some say he isn't. Myamoto isn't very specific here. I've heard one theory that he and Waluigi are the third and fourth Mario brothers, just sold to a circus and never again seen for a looong time. I've read reports on message boards that say in one Mario cartoon episode there were to figures that looked just like them. I haven't seen it, so I can't tell you much. Everything we see says Wario is Mario's childhood playmate, nothing more, nothing less. From this, we can see that Mario and Wario are not related, or it would have been otherwise specified.
Case Solved

Case 3: The princess' dropped name.
All of a sudden in Super Mario 64 we see no Toadstool but Peach! This was the princess' original name over in Japan but changed when it moved over to here. Nintendo gave us a clue a little before they let the cat out of the bag by making Belome say that Toadstool tasted "peachy". But anyhoo, because of the drop of the last name, some think she is now Mario's wife. Since they're married, they call each other by informal names. Also, that cake at the end of SM64 is theorized to be a wedding cake. Is this true? I say not, because over in Japan it has always been Peach. That would interfere with the plotline(two different plotlines for two different countries). Then again, Miyamoto isn't afraid of that.
Case Unsolved

Case 4: Mario vs. Wario
Only released over in Japan, all I can derive from this is that Mario ends up with a barrel on his head and Wanda the fairy guides him to safety. So has this happened to the plucky plumber, or not? If not, then one is forced to go with the Peach marries Mario plot almost... but then what if you DO want to consider the game som'in'? Do you get a ROM? I can't download any ROMs so I'm just clueless. What happened here?
Not Even Sure This Was a Case

Case 5: Mind Switch
Today, many mistake Mario and Luigi for different characteristics than they actually have. Mario is usually the bumbling fool who can't wait for lunch, while Luigi is dignified and comes up with brilliant plans. This is, in fact, quite the opposite of the "truth". If you'd read the early Nintendo Power comics(I don't know about the cartoons) they'd give it simple and clear: Mario passes all temptation, keeping Luigi out of trouble while he's looking for lunch. This is very odd, I know, but it IS what they(Nintendo) hints to. I don't know about Myamoto... Does he have the same ideas? It could be so, for the cast that made the comic was almost totally Japanese. Supposing the comics were originated in Japan, were they made without Myamoto's look over like Super Mario Land? If we are supposing, though, that there are different Mario/Luigi attitudes in Japan and the west, then one has to follow the non-Mario vs. Wario storyline.
Case Unsolved

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