Bro did you not start this discussion with
this scene? Ofc Sigma Force were stronger than Ledgic but up until Planet M-2 no one was stronger than the strongest Majin Buu narratively speaking until Base Rildo who was stronger than the Sigma Force who got molly wopped by a Goku who admitted to holding back, which would make sense unless you want to argue SSJ Trunks > Mutchy > SSJ Goku > Base Goku > Lord Luud off of the premise that Goku needed SSJ.
Whhhhy would we put Mutchi below Trunks or above SSJ Goku?
Base Trunks only killed Mutchi by catching him off guard. Trunks only went SSJ to beat the weight of Mutchi’s telekinetic rocks. Similarly, Goku needed SSJ to beat out the spells Mutchi could perform, like breaking out of being captured by his Earth Manipulation and not to compete with him
physically. Even if we did ignore all that, Mutchi was beating Goku by
removing SSJ (by draining him of Ki and hitting him against a hard surface to break concentration to force him out the form) not overwhelming him with raw force. (Though he admittedly did do so to start that strategy with his Whips to begin his train and slam.)
If anything, it’s: Mutchi < Luud < Trunks < Goku. (It should also be noted that 2nd Form Luud is specifically
stated to be inferior to SSJ Goku and Trunks by the Narrator, and as Mutchi is weaker than that version of Luud, it means Mutchi could never exceed either of their powers in that fight).
Though even if we swapped out 2nd Form Luud and Mutchi, the difference is pretty minimal given neither scale to the SSJs.
Goku getting a stronger boost in any of those scenerios would entertain a GT Goten and Trunks being stronger than Base Goku.
Also note, I don’t find this compelling at all. By Pital Baby has all the power of Level 3 Luud, (and MORE) with both Goku and Trunks struggling to defeat him in base at that stage (needing to target a weak spot). Even ignoring that, by Pital Baby's also hopped into Rildo, and as we know when he possesses a body he siphons off their powers. Not to mention it's pretty clearly established that (Infant) Baby's power on
awakening was "unreal" compared to anything they'd seen before that. And then when he possesses Trunks on Pital, Baby goes on to say "His power is UNBELIEVABLE!!" Taking on Trunks in his eyes gave him an
insane power boost, and then Trunks with his Saiya Power ("Am I really not strong enough? This this the TRUE depth of SAIYA POWER?!") was enough to eject him because his power was simply
just too much. A Rildo + Luud + MORE combo found
GT TRUNKS "too strong." By all accounts, Trunks
is stronger than Buu (logistically). But obviously that doesn't make much sense when out of the two,
Goku was the only one capable of handling Rildo. So either A) Trunks grew between those moments or B) Trunks was secretly the strongest on the team. (This also occurs again. Despite powering up
significantly, Goten for him was a
MAJOR JUMP in power. He makes note of this directly, how despite failing with Trunks he's "finally attained this unreal Saiya power" and how Goten "is power, FULL of power!")
Similarly, Goku
explicitly could not handle Ledgic in Base. He
needed Super Saiyan. This is something we're
outright shown and told. It's
not debatable. Yet RIldo is "the
first stronger than Buu." (Which isn't stated. While this
is the first time Goku has
directly made the comparison, Goku doesn't say
no one else is on that level. Though admittedly it's a moot point since that's obviously the
intent of the scene). So either Goku got stronger, or Goku sandbagged (
explicitly not correct). This take also doesn't make much sense when Zenkai Boosts exist in series. No matter what, after each battle they
necessarily get stronger. We also know that the Mid-Battle Zenkais exist within the Anime, because as Goku and Cell fought they were growing more powerful passively just from experiencing battle. So while there isn't a moment of "AHA, they got stronger!" from thing like training, or calling attention to Zenkai Boosts (at least until SSJ4 comes around and allows nullification of techniques as well) for increases in power, we
know they are growing in battle.
Either the characters stagnated and the plot twists in on itself or the characters grew. (It should also be noted that Goku "admitted to holding back"
specifically to Mega Cannon Sigma, not everyone else. In fact, he says "the reason why I did is
because you have my data." So this line of logic doesn't even make sense.)