Giving more context for Kuuga's experience (which all that comes from his profile basically but just to summarize), he had mastered
2000 techniques during his world-travelling and he perfectly remembers not only all of these,
but to which people he shared them in specific. He could unlock the Titan Form by just
training kendo with Ichijo and could ride the
Trychaser 2000, which is a police-purpose super bike that nobody had tested before, and he could engage it to fight a Gurongi with no issue. He could already transform into Kuuga one day after he absorbed the Amadam
through sheer will and
keep his own against Gurongi who have likely thousands of years of experience (given how Riku was already
mummified and found within ancient excavations when they found him). He could quickly
solve Go-Zazalu-Ba's attack pattern, something that officers and detectives couldn't.
Shepard is far superior to the likes of Asari Commandos who's race can live for 1000 years, these fighters can 1v1 any member of a species in mass effect like Turians who are so hyper militarised their army is also most goverment services and when the reaper invasion hit they held out the longest as every city on their homeworld was a goddamn fortress. There is also Garrus's feat as well in ME2
The Serrice Guard band of Asari did a
feat like this and Shepard would be far superior to these commandos given how he can fodderise AC's even in the first game. Shepard can also fodderise
Krogans on the regular, who can also live past 1000 years as shown with Okeer and Drack with Wrex (Who as a Krogan Battlemaster is stated to be able to solo ten soldiers of any race including the Asari) being close to that age. The Krogan homeworld is so hilariously lethal its
described like this.
And to enter a clan a Krogan must undergo a
rite of passage, fighting
waves of the predators of their homeworld which included Thresher Maws which can devour and oneshot them. Krogans are so entirely focused on warfare to the point where they so good at it that they were required to kill the
Rachni when no one else could. Then afterwards the Krogans turned on the citadel council and were such a pain that the Turians and Salarians had to unleash a s
pecies wide neuter bomb to them to cull their numbers. And Shepard fodders any Krogan he goes up against.
I definitely agree that Shepdard should take the skill categories, no doubt. They has far more experience and dealing with just as exotic threats as Yusuke has.
The main problem is the AP gap and Pegasus' from Gouram. That thing is a nasty combo. Allowing Kuuga to snipe his enemies from a much further range with impunity. Of course, there's several downside and way for Shepard to work around but Yusuke can definitely play the keepaway game here, especially with Gouram's assistance.
Shepard already casually upscales from his calcs to begin with and can amp himself further with
Adrenaline Rush and Immunity for his AP and Dura. He also has medigel for healing which can be done with just the press of a button, Shepard can also perception manip to see targets in slow motion during AR. For LS Shepard could shank Kuuga with an
omni tool blade if grappled to force a release I guess. Concussive Shot can stun targets too if not outright floor them too, granted that's likely due to LS bowling them over but even larger targets than Shepard can be staggered by it iirc.
I'm gonna ask on the topic of ice and heat manip, I think I saw Kuuga resists but I think its worth mentioning that Shepard's incendiary ammo and cyro ammo can reduce targets to ashes in seconds and also flash freeze and shatter targets to pieces respectively, which works even on geth which are purely inorganic. Shepard's other ammo types can be changed into with just a button press, Shredder, Armour Piercing and Disruptor Ammo will all serve useful here in tacking on damage.
Stamina both are comparable, I'd argue Shepard edges out due to being superior to the likes of Garrus, who spent over 24 hours in constant combat in a one man siege where he fought dozens of mercs from three whole groups, as well as dozens of freelancers and a freaking gunship all with little to no pausing. Shepard also gets
lazer'd in the last mission of ME3 yet still survives and carries on even with his armour melted and thensome. For range that might be an issue but Shepard would just pursue and stay in cover, did it one time while
avoiding reaper lasers
Thinking it all over I'm gonna vote Incon here. Kuuga has a sizeable AP edge still and has better range and his acrobatics should help in travelling the battlefield better and playing away if he needs to or close the gap. His LS is also an issue if he decides to just break Shepard's neck or smth.
Shepard meanwhile has the much greater skill edge, can amp himself to help cover the gap, has healing to keep going and he can perceive Kuuga in slow motion and light him up with bullets even if his ice and heat ammo can't do it he still has other types that deal more damage. Both can seemingly fight to the tenth round too so that's a toss up, so I'll vote Incon here.