trypticon would have his ass for lunch...eventually...

 

I wish Shockwave would have been featured in Season 3 and maybe would've tried to take command of the Decepticon faction. He was another great character just pissed away towards the end of G1, and he is definitely a major badass.

 

I don't think G1 Shockwave would be much of a threat to Starscream, in cartoon continuity. He couldn't shoot straight and Starscream even muscled him him over in one or two season 2 eps.

As for whether Starscream be a good leader of the Cons, probably not. While he's had a few flashes of brilliance it's outweighted by his massive failures. He would probably lead a losing war with an Autobot invasion of Cybertron. If Unicron were a factor and he survived to be on Charr, he might be someone troops would gether around for no other reason than he seems to know how to make energy. Power rationing would be his only ticket to maintaining troop loyalty after that. It's what he did to keep the Combaticons obediant but even that didn't keep them in line for long.