First, here is a list of the Unicron created characters, along with the previous characters whom I believe they originated from -
Unicron created Transformers shown -
Megatron ----> Galvatron
Thundercracker (No PC) ----> Scourge
Skywarp (No PC) ----> The Armada* ----> Skywarp (3H Wreckers comic.)
Bombshell (No PC) ----> Cyclonus
Shrapnel (No PC) ----> Sweep 1
Kickback (No PC) ----> Sweep 2
Blue generic (No PC?, dead?) (Seen being jettisoned) ----> Sweep 3
Another generic (No PC?, dead?) (Unseen) ----> Sweep 4*
(No PC) = No Personality component (See Spark explaination below)
* = Doesn't leave Unicron for the new ship
Here we see Cyclonus, his Armada, Scourge and FOUR Sweeps. This means that two other Sweeps must have been created from unknown Decepticons, off camera.

A mysterious, blue generic Decepticon, seen being thrown from Astrotrain, maybe another dead generic was jettisoned as well, in order to account for the 4 Sweeps being created? This generic is not an Insecticon, as they are shown being jettisoned shortly afterwards.

The 3 Insecticons are thrown out afterwards.

Previously, Thundercracker, Skywarp and the Insecticons are seen alive but damaged, aboard Astrotrain before being thrown out.

At least 4 Cyclonus clones (plus actual Cyclonus) are seen in Five faces of Darkness part 5.

Explaination of events -
Unicron may have kept the Armada and the 4th Sweep behind, to serve as substitutes for Scourge and Cyclonus, in case they and the Sweeps were killed off during their mission. Thus they never left with the others for Galvatron's new ship, but went inside Unicron and waited for further commands.
Explaination of clones -
At least two of the Sweeps (Shrapnel and Kickback) and possibly Scourge and the 3rd and 4th Sweeps can clone themselves as the Insecticons did. At least 7 Sweeps are known to have existed at any one time (Sweep 6 and 7 are named) so there are 8 altogether if the 7 does not include Scourge himself. 3 Sweeps and Scourge originally left Unicron, thus either 3 (7 total) or 4 (8 total) are clones of the originals.
Cyclonus (Bombshell) has higher rank than Scourge and the Sweeps, so only clones himself rarely when extra firepower is needed eg. in Five Faces of Darkness, Part 5. As with the Insecticons, these clones may require constant control from the cloner in order for them to stay in existence, this would take up all of Cyclonus's concentration, thus leaving his command position over Scourge and the Sweeps, compromised for a time, while his clones are active.
Both sets of clones are weaker than Cyclonus, Scourge and the 3 main Sweeps and can die more easily. It is also unknown if the Armada can clone himself but if Scourge and the 3rd and 4th Sweeps have been gifted this ability by Unicron then he would have this ability also.
The reason for the Insecticons (and possibly Skywarp, Thundercracker too) being seen later in the movie and Season 3 is probably down to them being rebuilt by the Decepticons in order to plug the gaps of the previous characters who were lost.
Spark explaination -
It is possible that the minds or "Personality components" of the Insecticons, Thundercracker, Skywarp and generics, were removed by the other Decepticons before they were thrown off Astrotrain. These personality components would be the holder of the transformer's Cybernetic personality, or Spark in later canon, which was once granted by Vector Sigma.
This has presedent as Megatron once ordered a group of political prisoners known as the "renegade Decepticons" stripped down to their personality components and put into storage on Cybertron.
Starscream later installed some of these personality components into his new combaticons, bringing them to intelligent life (Episode 46, Season 2 "Starscream's Brigade"). See - http://tfwiki.net/mediawiki/index.php/P ... _component
Similarly, these removed personality components could have been installed in rebuilt versions of the Insecticons and maybe the 2 seekers in question, under Starscream's orders. The issue with the two seekers is a bit difficult because Thundercracker is obviously shown as being "Dead" in the crypt during Starscream's Ghost (Season 3, Episode 16), so his "appearence" at Starscream's coronation could have been just a similar generic Seeker. The death memorial of Thundercracker is only refering to his body, as his personality component was known to have been preserved.
Skywarp is a different matter, if we take the 3H Wreckers comic as G1 cartoon canon, then the Armada is later made back into Skywarp again. In The Wreckers part 04 - Finale Part II (published only as text), this Skywarp is said by Cyclonus to have had his "personality matrix" restored, which probably means the same as personality component. Skywarp certainly seems to retain Skywarp's memory of Cyclonus as a "bug" (Bombshell) which would be expected if his previous mind had been restored. So if we take this as canon it means that Skywarp and probably Thundercracker too had their personality components removed, as the Insecticons did. The Seekers seen at Starscream's coronation were still probably generics, why would Skywarp be resurrected twice?
It was probably Galvatron who had him resurrected, after Unicron was killed (see explaination below).
Starscream probably chose to only have the Insecticons rebuilt and didn't bother with the two Seekers, as they were seen as more loyal to Megatron than the more independent Insecticons.
It is unknown if Thundercracker had a new body built, on Galvatron's orders later on (obviously Scourge wasn't changed back into Thundercracker).
This would mean that Unicron must be able to grant new cybernetic personalities and personality components (later termed as Sparks) to the dead shells of the Decepticons when they are reformatted.
Unicron must in this case have access to the "Allspark" as does Vector Sigma. Later canon shows that Vector Sigma is really Primus in another form, thus it is possible that both "God" robots have Allspark access.
See - http://tfwiki.net/wiki/Reproduction#Resurrection
Explaination of the Armada becoming Skywarp again in the 3H Wreckers comic -
If we take the Wreckers comic as G1 cartoon canon, then the fact that the Armada is later changed back into Skywarp again could be explained like this - The Armada and the 4th Sweep were probably killed or badly damaged, when Unicron exploded in the movie. Maybe the 4th Sweep was lost but the body of the Armada must have been preserved somehow, then was found by the Decepticons who showed him to Galvatron (the only one who would recognise him as being Skywarp previously). Galvatron, not wanting a sentient Cyclonus lookalike (due to Cyclonus's second in command position), had him restored back to his old servant (as Megatron) Skywarp. Skywarp's personality component may have been stored inside Astrotrain when it was removed from him, but maybe elsewhere. Skywarp then worked in the background for the Decepticons, for unknown reasons, and is not involved in the later cartoon storylines. Later, during the Universe storyline, Skywarp has his body changed to his Universe Aero Drone model (based on Beast Machines Jetstorm), for more unknown reasons and is seen and involved with Cyclonus in that storyline.
Cyclonus and restored Skywarp together.

Starscream's coronation seekers, must be generic seekers, the Insecticons were those rebuilt and restored under Starscream's short command.

Thanks for reading my fanon explaination




