Who is this?

[Flare]

So...
I'm resetting my town, and I noticed that behind Rover, there is a monkey...
Who is it? Is it Porter?

 

[Dolphishy]

I think most people agree that it's not Porter, since he's waiting for you at the station when you arrive. It must be another monkey that conducts the train!

 

[Buster Bunny]

I recall of someone calling him "Speaker", but it doesn't make sense.

Since "speaker" would be someone speaking off-screen.
Besides it might meant the monkey is talking through a speaker.

 

[GreenLeaf]

I always assumed that the railway service is run by a bunch of unnamed monkeys that are refferred just by their role

 

[That Marshal Fangirl]

It's Porter's twin brother, of course!

 

[Flare]

Yeah, probably is.
But...but... what if it's Champ?

 

[Blueskyy]

I, too, came here to hop aboard the Champ conspiracy train.

 

[ZebraQueen]

I, too, came here to hop aboard the Champ conspiracy train.

Likewise because champ just like to ride trains
And porter and champ have different birthday so maybe that monkey in the train it's champ and porter it's just it's twin brother
Maybe

 

[Xara]

i think that its champ, but i dunno

 

[Buster Bunny]

Both have different b-days but is really Champ, if he is the train conductor, then he could be a younger brother.

 

[Barnabus_i_am]

The monkey is called "Speaker" I'm the beginning when he announces that you are about to arrive in your new town, but his name must not really be Speaker... That would be so cool if it was Champ!

 

[SweetLamb]

Also on the Champ bandwagon (or train...) especially after the Porter = Champ theory was debunked. The train conductor monkeys don't seem to be anyone specific otherwise.