ACCESSORIES, HOW DO THEY WORK

I might have been extremely ignorant during my runs through HG, but a single question kinda pops up every single time I play, and I cannot seem to find an answer for it, so help me out, /p/okecommunity! I'll present it in a limerick;

When the pokemon that follows you around
finds something like trash on the ground
do you let it stay?
why don't you throw it away?
Its purpose in HeartGold is GONE

(yes the ending wasn't that great I know, but the point is still made)
DO the crappy items (or in some cases, emotions or w/e (yes, I'm looking at you Quagsire, why did you do nothing but find determinations at the rocket hideout, only to give it to me? Are you telling me that you cannot remain determined for more than three clicks of the button "A"?)) that your pokemon picks up during random times during your journey have any purpose in HG/SS? As far as I know, contests are unheard of in the "civil" Johto (sure, I'll give you that dress-up is inhumane, but working your mons to death in the arena is something completely different, "oh yes it is", and you can even buy drugs to increase their performance with unknown side-effects, BUT I'm not going to rant about that now) and as such, the pokethlon is where the cool kids hang out, and if there's one thing I know for sure is that I would LOVE to shove those >9000 determinations back into quagsire where the sun doesn't shine, yet it appears that I am unable to do that.

Tl;dr, can you actually do something with the pokethrash?


HALP ME

You get to dress up your Pokemon in the Goldenrod Underground. That's their only use, pretty much.

I'm not gonna lie: I legitimately LOL'd at that comic.