Masaru. Before training with BanchoLeomon he already punched and damaged several Mega Digimon like Saber Leomon and Mercurymon (the Olympus XII member, not the Legendary Warrior).
Masaru breaks one of Saber Leomon's fangs.
He is durable since he is ok after being attacked by the bio digimons. This takes place after BanchoLeomon's training.
In the movie, he punches Algomon in Mega level.
BanchoLeomon stops one of Masaru's punches after this.
Masaru punches Belphemon, one of the 7GDL, twice.
Masaru takes several of Craniumon's attacks and stops his lance with a punch. Masaru manages to knock down the Royal Knight twice. In their second fight, Masaru destroyed Craniumon's shield.
He also damages Dukemon with a punch.
And destroys Yggdrasil's body (Saving the Chosen Children from Alphamon and stopping the events of Tri
).
In Xross Wars, Masaru punches a Venom Vamdemon and destroys three Belial Vamdemon with his digisoul.