So Masato Mizuta is credited for voice work in several Mario spinoffs. Several sites, including this one, pin his role to that of Monty Mole.
But Monty Mole, to my knowledge, only appears in three of the games Masato Mizuta is credited for voice work in (the Wii version of Mario & Sonic London 2012, Mario Party: Island Tour and Mario Party 10). And I'm not even sure if Monty Mole is voiced in Island Tour. That leaves four definite outliers: Mario & Sonic Vancouver 2010 (both DS and Wii), Mario Tennis Open, Mario & Sonic Sochi 2014 and Mario Tennis: Ultra Smash. So either he's more characters than just Monty Mole or he's not Monty Mole at all.
I'm sorry if this is a weird topic to bring up but I figured this was the best place since he's a Nintendo employee, not a professional voice actor.