>>19820382Bipeds (winged Pokemon included) are measured by standing height.
Serpentine critters are nose-to-tail length.
Jury's out on whether quadrupeds are to the shoulder or crown of head.
Someone always tries to say winged Pokemon are measured by wingspan "like real-life birds" (not strictly true), but that doesn't seem to be the case in any kind of media.
Anime sizes are inconsistent even within their own canon, let alone with the games.
Also no one knows what the fuck to do with Crobat. It's huge no matter how you measure it.