Skimmed through the issues Jenny Fractal appeared in, just to confirm my suspicions... There is no way in hell she can compete with EJ. It's spite, tbh.
I did say he was universal, not multiversal. Taking the powers to their ultimate conclusion, EJ may well have been multiversal, but we never saw it. His feats still beat the living hell out of Jenny's best, both in theory (reality warping > matter and energy manip., regardless of how powerful it is) and in the comics themselves (scope is much greater for EJ's feats).
Add the fact that Fractal had all of one arc (6 issues if memory serves) and even if we grant her Quantum's potential, she loses hard.
Jenny can kick ass, but you need to stay away from those with borderline abstract power (or not even borderline imo, in EJ's case). Team-wreckers, anything up to about Skyfather, that's her wheelhouse.
When you start pitting Trans. + characters against each other, discussions quickly switch from figuring which character would beat the other based on powersets to measuring which character simply had better feats - because eventually they all have the same powerset on different scales.
In this case, the scale and scope of EJ's feats demonstrably outclass those of any Jenny.
Cosmic is pretty much *always* 'who's the bigger scale,' and it's actually somewhat uncommon for cosmics to be at the same level, and someone of higher level can casually beat large numbers of those at lower level, so I find cosmic fights to be among the most boring.
Really not sure where you're getting these. This is about the third incredibly vague feat you've referenced. Read her respect thread (in the Authority respect thread). It might not be 100% complete, but it doesn't leave out anything important.
I never read Solar, so this is a bit of a guess. His feats (in his "prime") seem like they were more epic in scale. The Doctor would have the best chance. It was directly implied that he was more powerful than Jenny, and also has a bigger variety of ways to attack Solar. I'm not sure how Solar would react to, say, being force-fed billions of lives worth of mental pain.
Not sure why this matters--Jenny certainly did not warp a multiverse. That was her plan, yeah, but it was a plan she never came remotely close to achieving. On panel, she warped various portions of the earth--and that was done by concentrating her power through her ship.
On panel, EJ destroyed the universe, easily. Recreated the universe, easily. Controlled every facet of said universe, easily. Controlled the Spectre entity, easily. Controlled the Qunitessence (whom represent a HIGHER authority than Spectre), easily. He dominates Jenny in every aspect.