Eggman being potrayed is physically comparable to Sonic seems inconsistent or contradictory to him normally using mechs for most of his fights.
I once agreed with this, as I also once thought this was inconsistent.
Till you realize outside of the Egg Mobile, Eggman/Robotnik never fought Base Sonic in a Mech,
till issue 175!
The first Mech suit Eggman wore was the Eggs-O-Skeleton, which Sonic had to use Silver Sonic as suit to fight on par with. (Sonic Quest issue 3)
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When Eggman became a Robot, Base Sonic can’t even hurt Robotnik like he could when Robotnik was Organic. (Issue 75 & Issue 118)
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Then Issue 175 happened, the 1st time Sonic in Base fought a Mech, the Egg Beater, Sonic can’t hurt the Mech all with his regular Spin Attacks he has been using the entire Comic. He ultimately had to rely on his Freedom Fighters and the Chaotix to destroy the Egg Beater, with their own unique abilities (Issue 177).
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The 2nd time Base Sonic fought a Mech, the Egg Phoenix, Sonic didn’t even attack it, but he follow Sally’s plan to defeat it and it was stated before Sally’s plan that Eggman was winning. (Issue 198)
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The 3rd time Base Sonic fought a Mech, the Egg Tarantula, yes, Sonic beat it, but Sonic also noted it’s not the same as the Egg Beater. This was also the time Eggman was losing his mind. He completely loses his sanity after this fight is over. (Issue 199 & 200)
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The 4th time Base Sonic fought a Mech; the Egg Tortoise, we get no scaling from this but Sonic admits he was holding back. Eggman completely lost his mind at this point. (Issue 205, a few panels later, Eggman punches Sonic in face that made Sonic take a moment to recover)
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The 5th and Final time Base Sonic fought a Mech, the Death Egg Robot, Sonic completely has no way of fighting it, other then transforming into Super Sonic. Eggman has recovered his sanity at this point. (Issue 229)
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So, no, in terms of Archie verse Lore, I can't find Dr. Julian Ivo “Eggman” Robotnik scaling to Sonic in his Organic Base form inconsistent.