This is definitely a match that Renamon can win. “Even though he is a mega, this Digimon is virtually powerless and it can defeat a champion level opponent when in great numbers.” I’m paraphrasing a little from the Digimon wiki regarding ​Dokugumon’s Mega form, but that’s pretty sad when you think about it. Renamon’s champion and ultimate forms are not particularly impressive, but her Mega form would easily crush ​Dokugumon and Renamon may stand a decent chance in her rookie form. That may be pushing it a bit, but she definitely wins this round with ease. Renamon wins.