I don't actually know if there's a solid norm for this (gonna explain later) but that's how I see.
In the case of Poros, Titan and Chao and others, they are fictional living creatures but they don’t have many individual and singular characters based off them. Same thing for most Pokemon and monsters from Monster Hunter. (although in the case of Titans, the tag is supposed to be used for generic non-intelligent titans, not for the nine titans from titan shifters which have individual tags).
Now in the case of Draphs, we have a lot more individual and intelligent characters that are from that species/race. For other races like Elf, Orc and Goblins, they are not a character tag because they are more generic and appears in tons of different copyrights, while Poros are much more unique to their copyright, so there’s also this factor.
However if we followed this pattern, I think fictional races in Final Fantasy like Miqo'te and Viera should be general tag, not character tag, so this might become an issue.
I don't know much about LoL (correct if I'm wrong), but Poros seem like Chao from Sonic, a mascot creature from their world, don't have complex human-like intelligence, has some few individuals (like Cheese and Poro King).
Now what if they were one of the main races the player could choose in a game, and we had more intelligent and human-like characters from their race, I'm pretty sure they would fit better as a general tag instead.