[] Stick with training. At worst it will make him a little more powerful, but he won't digivolve.
-[] Tell him digivolution won't solve things forever. Each step is harder than the last. What separates good mon from ferals is the ability to think and learn. Skill and knowledge are harder to hone, but offers power beyond the limitations of a mon's frame. Let him know how long you took to digivolve from Drimogemon, the time it takes to attain the next stage is time available to strengthen his core, so that his next stage has more to build upon. Unless he is in need of immediate power, he could always refine his skill and knowledge further, and strike with the force of one a stage higher.
===
You spend five entire seconds considering the matter, which allows for quite the lengthy internal debate. The warrior part of you finds Sparks' plan very appealing, earning one's evolution through a difficult duel would be a spectacular way to go about it. However, said method could be notably dangerous to your pupil... plus training to evolve is almost equally as appealing.
In the end you decide upon the slower route, as even if the training doesn't make him digivolve, your theorized special training should help him grow as a martial artist.
However, before explaining that… there is another matter that needs to be discussed.
So after quick nod of affirmation, you kneel down next to *Boy* and look him right in the eyes.
"Are you aware of how much time I spent as a Drimogemon?" The Champion blinks at that, then puts a fist to his chin in thought.
"Maybe… a month sensei?"
Less than forty days… how short that falls.
"Eighty-Eight days."
"Wha-what?" *Boy* jerks back at your answer in surprise. "You can't be serious… by the Ten you are! How… for that long?"
"Aye. Followed by one hundred and forty days as Gryzmon. My evolutions have always taken longer than those on a similar path." While he continues gaping, you can't help but smile in pride. "Most would consider that flaw a handicap, but I believe it be a crucial part of my power."
"How does that… I'm sorry sensei, but I don't understand. How does evolving slower make you stronger?"
"Hrm… a number of reasons. My limits have always been greater than others, allowing for a stronger foundation upon which to digivolve." You admit, as it would be irresponsible to leave out your benefits. "However my primary point is, that the lack of physical growth fueled my heavy focus on skill and knowledge. Both are more difficult to hone and rarely bring immediate results, but lack the frame's physical limitations."
"I… remember hearing about you defeating Ultimates when you were still a Gryzmon." *Boy* murmurs thoughtfully. "I'd thought you were just stronger than them…"
"I possessed more power than some. But many a foe was beyond the reach of my strength alone."
Even with my equipment, MadLeomon would have deleted me had I fought only using brute strength.
"It was through skill, and leveraging the enemy's weakness that I found victory..." You trail off for a moment, eyes drawn to the black and red pauldron on your shoulder. "And utilizing my own special equipment."
"Those… hahaha. I uh, don't think I can copy your armor sensei." He chuckles, falling into a warm smile that matches your own.
"No, you cannot. However the former points apply. And even as an Ultimate, you will one day reach that form's limits as well." You raise a hand, and very lightly prod his forehead with a finger. "What separates a true warrior from ferals or the ordinary is a willingness to continue training and accruing knowledge, even if the immediate results are slim. Each step forward on your path will be more difficult than the last, but one must still persevere."
"I… think I get it sensei." The Aegiomon nods thoughtfully. "Sorry for umm, complaining at you earlier."
"Frustration from a lack of progress is understandable. I suffered from that myself." You explain warmly, before settling into an utterly serious tone. "The training you're asking for will push you to the very brink physically, and mentally. Are you certain about trying it?"
"I…" He gulps, then clenches his fists in determination. "Yes. What do I have to do sensei? Fight you?"
"That would accomplish little at your current level." The flat dismissal makes him flinch, but ignore it and continue onwards. "I've already considered this possibility and will model your training after… the regimen another mon put me through."
"Oh no." *Boy* whispers, his eyes widening in horror. "You're going to make me train like… you."
"Aye." You confirm, taking just a little amusement in his reaction. "But that will be for tomorrow. Continue your normal katas and spirit manipulation exercises for now, I must purchase a number of weights from Gorimon's gym and finalize the training plan."
"I-maybe we shouldn't…" The Champion trails off into a strangled sound before slumping in defeat. "Yes sensei."
===AN: This is probably two thirds of the update. I'll be working on the last bit after a short break, and it'll have the vote.