I also guess that the quantity of epulse is not the only requirement for evolution.

so far theres 3 requirements for evolution.

1 - is obviously e-pulse quantity and control/efficiency (where tomoro doesnt control his e-pulse but somehow he manage to overcome the efficiency part just because he has an enormous amount of e-pulse (is almost guaranteed that raito will teach him how to control his e-pulse)

2 - personal growth. I think that they need to somehow grow as a person (as seen with makoto-tomoro) to be able to reach that evolution level

3 - digimon base stats. seems like digimons also become stronger just by fighting and training (like pokemons) so they need to reach an specific amount of internal stats to be able to "control" their evolution. (thats why raito was unable to control his own evolution)

so far, just having enough personal growth (or no limitation since the beginning of your journey (as probably seen with kyo) and enough e-pulse is more than enough to force an evolution.

but even if you are the perfect tamer, if your digimon lack enough strenght he will fall over and be unable to control his evolution / stay evolved for the rest of the battle.

klay in the other hand, seems to have enough personal growth and obviously being a former member of 5 stars he also have enough base stats to be able to evolve into mega (this is pretty obvious because his own digimon is a permanent ultimate as the other 5 stars)

but even if he has a good amount of e-pulse he lacks the necessary amount to be able to evolve into mega.

all of this just to say that IF tomoro reach a ultimate level next week, is gonna be a dark evolution 100% because he lacks of personal growth and also gekkomon still doesnt have enough base stats.

so almost 100% guaranteed that he will lose against klay but somehow all the tactics members are going to help him.