There's no particular way you need to do it. You should just mention where you got it from (e.g. with a link to the exact page it came from). It doesn't have to be different from the way you'd normally put references into your post.
I wrote a thread about referencing a while back -- that's pretty much the extent of my thoughts on when/how to reference.
https://pokemondb.net/pokebase/meta/72229
