Personifications of all of the mouse pokemon, sans their pre or post-evolved forms. Some of these appear in some of Tachitsu Teto's other moemon posts.

cyndaquil is an echidna.........

True, but his Dex entry says Fire Mouse.

Mouse, Rat, Mouse, Aqua Mouse, Fire Mouse, Plump Mouse, same difference to the artist, I guess.

and yet the actual mouse creature apparently does not exist in the pokemon world

so then how are pokemon classified if the animal they are being compared to doesnt exist!!?

I guess that either they do exist there, or used to but are now extinct.

I think the real mouse do exist, but they aren't as special.