Porter

The porter (えきいんさん, Station Worker) is a monkey who runs the Train Station in and. He coordinates transportation between villages. Little is known about him, and he never re-appeared in future games of the, although this changed when pre-release footage of Animal Crossing: New Leaf was released, depicting him running the train station once again, but also with a railroad crossing (but his name was changed to Champ). He strongly resembles the villager, Champ, who appears in and City Folk. He is a brown monkey with a pale yellow face, hands, and feet. He wears a blue station porter uniform, with gold buttons on his jacket and a badge on his hat.

Dōbutsu no Mori, Animal Crossing, and Dōbutsu no Mori e+
In these games, he is the Train Station porter. He can be found at the Train Station.

Animal Crossing: New Leaf
Champ will appear as the porter in this game.

Same
Fans have speculated that the porter and Champ could be the same person, due to their close physical similarity, along with the fact that they have yet to appear in the same game, and many other things (like Champ's interest in trains). Nintendo has connected the two by making Champ the porter of the railway in New Leaf.

Relative
Due to Porter and Champ's close physical similarity, along with the fact that they have yet to appear in the same game, suggests that they could in fact be related to each other.