Hey, I just thought on stuff to add to this, finally! After, like, a month. Sorry, few folks who actually care. D:
So this time, I'm gonna try checking each movie and noting how events in each often parallel to/callback on events in the TV Series by that point. Let me start with the first three, of course.
Movie 1:
1) Piccolo is shown to be weak compared to the new antagonist, Garlic Jr's henchmen (Piccolo is shown to be weak compared to Radtiz, who is not even close to demonstrating his full power. From the early Saiyan arc.)
2) Gohan is kidnapped, and Goku heads to the location of the antagonist to get him back. (Same. Early Saiyan arc.)
3) Garlic Jr. gets a wish for immortality from Shenlong. (Piccolo Daimao wishes for eternal youth from Shenlong. Piccolo Daimao arc, earlier DB.)
(blah blah skip some scenes...)
4) Piccolo forms a "temporary" alliance with Goku. (Same. Early Saiyan arc.)
5) Goku and Piccolo attempt to double-team Garlic Jr, who they can't fight on their own, but Garlic Jr. can't die because he's immortal. (Goku and Piccolo attempt to double-team Raditz, who they can't fight on their own, but Raditz still outclasses them. Early Saiyan arc.)
6) Gohan grows enraged and unleashs a burst of power at Garlic Jr. when it appears that he'll have everyone trapped in the Dead Zone. (Gohan grows enraged and rams his head into Raditz when it looks like Raditz is gonna kill Goku. Early Saiyan arc.)
Movie 2:
1) Dr. Kochin gets a wish to unleash Dr. Wheelo from his containment from Shenlong. (While not related to immortality, this still kinda relates to the Piccolo Daimao thing again.)
Interestingly enough, this is the last time in the franchise to this date an antagonist character succeeded in getting a wish.
2) Piccolo rescues Gohan from... them Saibaimen-like robot mooks. (Piccolo rescues Gohan from surprise Saibaiman attacks. Latter Saiyan arc.)
3) Gohan is shown as being attached to Piccolo, and vice versa. (oh, c'mon, this one should be obvious.)
4) Goku uses a basic Kaioken to defeat Dr. Kochin's robots when Gohan and Kuririn are in danger. (Goku uses a basic Kaioken to defeat Nappa when he rushes towards Gohan. Latter Saiyan arc.)
5) Dr. Wheelo starts out being interested in using Goku's body, but discards that idea after Goku resists stubbornly. (Raditz starts out wanting Goku to help him out, but discards that idea after Goku resists stubbornly. Early Saiyan arc.)
6) Gohan snaps and unleashes a wave of energy at Wheelo for what he's done to Piccolo. (Gohan snaps and unleashes a wave of energy at Nappa for what he's done to Piccolo. Early Saiyan arc.)
7) Dr. Wheelo is so strong Goku struggles with him even at a basic Kaioken, so he unleashes a triple Kaioken to pummel him for a while. (Vegeta is so strong Goku struggles with him even at a double Kaioken, so Goku uses a triple Kaioken to pummel him for a while. latter Saiyan arc.)
Goku gets into a beam-of-war with Dr. Wheelo and wins by raising his Kaioken to a quadruple, but somehow knows that hasn't killed him. (Goku gets into a beam-of-war with Vegeta and wins by raising his Kaioken to a quadruple, but somehow knows that hasn't killed him. Latter Saiyan arc.)
9) Goku's first attempt at using the Genki Dama is interrupted with a blast that nearly kills him. His allies then come back to help him fight. The second attempt at throwing the Genki Dama lands a hit. (Similar, except Kuririn throws it on the second attempt and it doesn't end up being a killing blow. Latter Saiyan arc.)
Movie 3:
1) A Saiyan invades earth. (Hurhur. Early Saiyan arc.)
2) Turles appears to be related to Goku, briefly confusing people. (Raditz actually IS related to Goku, shocking people. Early Saiyan arc.)
3) Kuririn, Tenshinhan, Chaiotzu, Yamcha, Piccolo and Gohan all fight. (Same. Latter Saiyan arc.)
4) Kuririn misses with the Kienzan. (Happened so many times in the TV series it's actually more shocking that this isn't a running gag in the movies.)
5) Gohan is shown as getting stronger and being able to hold his own better. (Same, early Namek arc. BTW, he's got the haircut from that arc starting in this movie, and it stays that way until movie 6.)
6) Gohan is transformed into an Ozaru when looking at an artifical moon, and to get back to normal his tail is cut off. (Same, although the protagonist/antagonist roles in this are reversed. Latter Saiyan arc.)
7) Ozaru Gohan is calmed down and prevented from attacking allies, and goes to fight the villain. (Same. Latter Saiyan arc.)
Tenshinhan, Chiaotzu, and Yamcha don't really stand a chance. (Thankfully, none of them die, unlike in the latter Saiyan arc.)
9) Goku does (What at this point is considered) an absurd Kaioken multiplier, but it's a no-sell to Turles. (I don't think it happened yet by this point, but the same thing occurs when Goku battles Freeza.)
10) As with the previous movie, it takes two tries for the Genki Dama to land a hit.
