Let's see (prequels vs. Classic Trilogy):
Chewbacca swinging on a vine with the Tarzon yell to attack a massive metal vehicle...
Dooku vs. Anakin while Palpatine watches / Luke vs. Vader while Palpatine watches...
Palpatine & Windu while Anakin looks on / Palpatine & Luke while Vader looks on...
the Ending shot of AOTC / the Ending shot of ESB...
Opening Crawl and pan to a ship or planet in each movie, iris to space credits at the end.
THX-1138 reference, cast & crew cameos, and other "easter egg" in-jokes (shoes, potatos, whatever).
"virtual unknowns" cast as major characters, with veteran actors in a few supporting roles (Peter Cushing/Alec Guinness/Sebastian Shaw?/the guy who played Uncle Owen?; Liam Neeson/Sam Jackson/Christopher Lee/the guy who played Chancellor Valorum).
Diversionary battle to delay the enemy (TPM's Gungan army, ROTJ's Ewok army / Rebels on Hoth).
Lightsaber battle between "Father" and Son (ESB/ROTJ vs. ROTS. remember in AOTC "You're the closest thing I have to a father" spoken by Anakin to Obi-Wan).
Wheezing cyborg (Grievous) / Wheezing cyborg (Vader)
And lots of reversals too, like Boba Fett chasing the heroes / the heroes chasing Jango Fett. Stormtroopers as bad guys, Clonetroopers as good guys. Jedi fighting in war, Jedi talking against war. Rebels as good guys, Rebels as bad guys (Seperatists). Government as good guys (Republic), Government as bad guys (Empire).
And plenty of the usual stock stuff, starship battles, lightsaber battles, campy dialouge, comic relief characters (physical comedy and corny jokes), "I have a bad feeling about this," wisdom spouting characters, cackling villians, blaster fights, ground battles where one side is clearly outmatched, deus ex machina type resolutions, droids, cut off hands, humble characters becoming heroes, wolves in sheep's clothing, star ship/speeder chases, lost lightsabers, etc.