Dead Zone also doesn't make sense. Because then Goku would probably want to train Gohan himself. Or something. Point is, that new power of Gohan's is no longer surprising. Oh, and who the hell is Gohan. Goku has a KID!!!?
And, you're right, I did forget about those. Janemba's can't fit because it needs to exist in a scenario where Vegeta and Goku are both dead— where Gohan and Videl are together/he possibly has his ultimate power— where Goten and Trunks have Gotenks available— all without Buu...? My guess is it can be if Vegeta has successfully killed Buu with his self destruct..?
Lord Slug could also take place after the Saiyan Saga but before the Namek saga...?
But now, to make it make sense. We can do this 2 ways. Change the movies to fit Canon, or change the canon to fit movies. I'm gonna do what I think is cool, flip flopping between my headcanon where the other humans are relevant and when they're weak?
Obviously, Dead Zone takes place before Raditz. Krillin just met Gohan in the movie and doesn't know he's Goku's kid until the end of the movie. Then, after Goku and Krillin agree to meet at the reunion. Piccolo makes a mental note of the Kid's power.
Goku and Gohan go to the reunion, and the only one not there is Bulma— sick of Yamcha's stuff. The entire group is there, Tien and Chaotzu included. They get stomped by Raditz. They team up with Piccolo. Get stomped by Raditz again. Gohan Headbutta Raditz. Goku full Nelson's. Everyone has to watch Goku get Makan-capped in the ass, powerless to do anything. Raditz gloats as Goku dies. All of them shuffle over and stomp him to death after he chokes out that in two years, 2 more Saiyans will show up. Someone meantioned the Dragon Balls before killing them. Starting up the issues with the Saiyans. 2 years gives Goku enough time to train. Hops back to earth within a year and continues there. Either they stomp Nappa or both of them are still strong enough to give them a challenge, but Nappa dies, Vegeta loses, everyone lives. Then they die against Turles. Then Lord Slug comes here and they learn about Namek as he monologues or something? Goku gods false super Saiyan or taps into the real thing for a hot second. That's when Namek takes place.
Goku Beats Frieza using Super Saiyan. Cooler finds out. After Frieza comes back, Cooler appears in the middle of the gap before androids 17 and 18 come out. At some point before that, they already wished everyone back and for new Namek btw. Goku kills Cooler, Cooler comes back, Goku kills him again on New Namek, along side the new and improved Super Vegeta, who came to new Namek after sleeping with Bulma.
Comes back, and Trunks was waiting for them. Turns out he forgot to mention, like, 3 more Androids that they defeated. Trunks wanted to help anyway. So that explains why he's there with them. He was just waiting for the Androids to show up. Left to go check on his time again though— maybe to have that Trunks be killed by Cell and another Trunks come by, ignorant of what the last one did. Fights Cell, who only needed the stronger ones, 17 and 18. Things proceed as normal until the Cell Games. In that 10 Day period, either cell went off planet to some place else to cause some destruction— went into a hybernation mode that made him miss Broly and Hatchiyak. In both of those movies, Goku and Gohan were in constant SS training, except for when they lost consciousness.
Cell Games. Then Bojack. Gohan stops training because school. Picked it up before the tournament. Trained Videl. In that gap, Broly 2 happens. Tournament. 18 wins. The Kais do show up, as does Spopovitch and Yamu. Everything plays out normally, except the whole process Babidi was on required more prep. So when they tried to go to the Ship, they were too late. It flew off planet again. The Kais stay on earth, knowing that they have to absorb Ki to summon Buu, and there's no efficient way to do it other than to use Earth.
Goku teaches the boys Fusion. Gohan and Videl hit it off. Ignoring the possibility that Gohan has Mystic, Janemba's movie happens as it should, except Vegeta fell into hell because of the laws of life and death being warped. The Kais had to go back to their own world to handle the issues with the Universe being warped by Janemba. Vegeta helps Goku, and at the end of the movie gets warped back to the Living World by King Yemma. The Broly 3 movie happens. A few weeks later, ya boi Babidi is back. Gohan and Vegeta go with the rest of the Z fighters to storm Babidi's ship. They fight Dabura, Pui-pui, and Yakon with no issues. Dabura fights EXTRA HARD against both Vegeta and Gohan, dying in the process of gathering enough energy to summon Buu. Vegeta and Gohan get stomped by Buu. Piccolo and the others could only watch. After Gotenks loses against Buu, Piccolo snatches up Trunks and Goten and takes them to train, bargaining with Buu for the "strong guy" to be ready in a day or so. Buu kills Babidi because he was trying to get Buu to kill Piccolo instead. Buu meets Hercule on his killing spree, and Super Buu appears. Piccolo and the rest of the crew, including Videl had to just watch on the lookout as this happened. Then Buu came to them and killed everyone but Piccolo, who almost died trying and failing to protect them. They trained and fought Super Buu, and Failed. Vice Shout scene happens. They do it too after training. Goku and the Kais had to watch as Buu and Gotenks fight. Gohan gains Mystic and saves them in the nick of time, but it's not enough. Piccolo and Gotenks get absorbed. Elder Kai gives Goku his life, and Vegeta revives too. Goku tried to fuse with Gohan, and couldn't, so he fused with Vegeta, and you know the rest. And Wrath of the Dragon happens before Battle of Gods. There we go!
