Eusine is a Pokemon researcher who is an expert on the legendary Pokemon of Johto and their myths.
He seems to have an obsession with Suicune and considers himself the only person worthy enough to capture it.
In the English dub version of the Pokemon anime by 4Kids Entertainment Eusine was voiced by Ted Lewis.
In the English dub version of Pokemon Chronicles Eusine appeared in "The Legend of Thunder"; a three episode arc. For some reason (error much?) Eusine was named Eugene instead. For these episodes Eusine was voiced by Dan Green.
In the English dub version of the Pokemon Generations shorts Eusine was voiced by Kyle Hebert.