Goku And Piccolo Vs. Raditz
The first Major fight in DBZ. Raditz appears to be having to problem with Goku and Piccolo. During this fight Gohan's true power is revealed. Gohan wasn't really in the fight because he only hit Raditz a few times when he saw raditz almost killing his father. Raditz is defeated when Goku holds Raditz still so Piccolo can use his Makansappo. This kills both Raditz and Goku. Afterward Piccolo takes Gohan so he can be trained.
Vegeta Vs. Goku
The second great fight in DBZ. Goku is not able to kill Vegeta. Yajarobie helps out by cutting off Vegeta's tail while he is transformed. Krillin and Gohan help out also. Krillin could have killed Vegeta with Yajarobie's sword, but Goku tells Krillin to let him go.
Goku Vs. Ginyu
At the beginning of this fight, Ginyu does not realize Goku's emense strength. Ginyu's powerlevel is around 120,000 and Goku powers up to over 180,000. At one point Jeice appears and grabs Goku thus giving Ginyu an easy chance to beat Goku. Ginyu says that he does not fight that way, though. Ginyu eventually uses his body switch technique to change bodies with Goku. Ginyu is later defeated when he tries to body switch again, but Goku throws a frog in his way, thus transforming him into a frog.
Goku Vs. Freeza
A very long fight so I will only give the main points. Freeza was forced to transform into his fourth form. Freeza killed Dende and Vegeta. Piccolo distracted Freeza while Goku formed his biggest Genke Dama or Spirit Bomb ever and fired it at Freeza. The Z warriors began to celebrate. Freeza was still alive and appeared from a mountain. He shot a beam through Piccolo which nearly killed him. Actually the beam was shot at Goku but Piccolo jumped in the way. Freeza then uses an attack to make Krillin explode. Goku then turned SSJ (one of the most classical moments in DBZ and my fav) and ordered for Gohan to leave with Bulma and Piccolo. So to move on Goku had the advantage the rest of the fight pretty much. Freeza was cut in half by a disc that he fired at Goku. Goku then gave Freeza some energy so he could escape the explosion. Freeza turned on Goku and Goku was forced to put Freeza out of commision by blasting him and hopefully ending the terror for good.
SSJ Goku Vs. Cell
This is the first equal opponent for Perfect Cell. The two exchange blows evenly and this match is too close to call. In the middle of the fight though, Goku gives up and says that Gohan will fight in his place.
Cell Vs. Gohan
This fight starts when Goku forfeits and lets Gohan take over. Gohan does poorly at first and reaches the brink of death. Goku keeps telling Gohan to "get mad", so Cell tries to make Gohan made by creating "Cell Juniors" which beat up on the Z warriors. Android 16 jumps in and tries to do a self-destruct to Cell. The explosion will kill everyone in the area and after a few minutes of anticipation nothing happens. Krillin remembers that Dr. Briefs took that ability away from 16 when he was working on him in his lab. Cell laughs and blows 16 into pieces. More fighting occurs and Gohan is beaten even worse. Later, the head of 16 (all that is left of him) asks Mr. Satan to throw him near Gohan. Mr. Satan regretfully agrees. When 16 is near Gohan he tells him that it is OK to fight for something you believe in and encourages Gohan to fight with all of his power. Just as he finishes speaking, Cell steps on 16 and destroys him forever. Gohan is enraged at this and everything that been happening so much, that it causes him to go SSJ2. Gohan kills all of the Cell Juniors with ease and easily beats up on Cell. Cell is about to die and Gohan is starting to toy with him. Goku tells Gohan to "finish him", but Gohan is so enraged that he says he deserves much more. Goku is shocked because Gohan is going overboard. Cell spits out 18 and starts returning to his imperfect body. In desperation, Cell uses his self-destruct and is going to blow up the world. Gohan is upset because he should have killed him and now there is nothing he can do. Suddenly, Goku says his goodbyes to everyone and uses instant Transportation to teleport Cell to King Kai's place. Cell regenerates after self-destructing (something he didn't know he could do) and has strangly learned Goku's Instant Transportation trick. Cell is back in his Perfect stage and as strong as Gohan. he uses Instant transportation to go back to the fight where Krillin is helping Gohan up. Cell Fires a giant Kamehameha wave at Gohan who only has one arm left working after saving Vegeta's life. Gohan retaliates with a Kamehameha of his own after Goku telepathicaly talks to Gohan and tells him not to give up. Vegeta distracts Cell after recovering and Gohan fires an energy burst into his Kamehameha and evaporates every cell in Cells bosy, not allowing him to regenerate.
Majin Vegeta vs. Goku
Vegeta lets himself get possessed by Babidi, so that he can get more power. After he does this Vegeta, Goku, and the others are teleported to the world tournament Arena. Vegeta blows up the stands to provoke Goku. Goku realizes what Vegeta is doing and that he let himself be possessed. Goku is outraged and agrees to a fight with Vegeta , even though Shin tells him it is just Babidi's way to gain energy for Majin Buu. Vegeta and Goku go to an empty location and start to fight. In the middle of the fight Goku senses Majin Buu and says that they should stop and go find out what is happening. Vegeta agrees and Goku lets his guard down because he thinks the fight is over. When Goku reaches for the last senzu, (he is taking it to prepare for the Majin-Buu fight) Vegeta hits Goku and knocks him out. He takes the senzu and flies off.