You can post your sketches in a new art thread that belongs in Art Gallery, but It's not necessary to make a new thread for sprites; just use your old one.

I've saved them in .png and reuploaded them, but as everyone said
their designs as "pokemon sprites" weren't good, so i'll sketch them
on papers before i upload the sprites, but to do that, i'll have to make
a new thread, so i wanted to ask you if that's okay :)

I don't think that. XD I just think you should be saving in .png. Anyways, if you want to add a large picture with a bunch of sprites, then that's fine too. It can be similar to a 'spritedex' so go ahead.

Hi, how're you?
if you dont mind, i just wanna ask you about something
...i'm sure you remember my thread about the 155 pokemon
... i was thinking of uploading them in large size pictures
since you think i'm not that good in making simple images for
pokemons like the original ones...
this way, i think they're gonna be more clear and look more
like pokemons.
Don't worry about the quality, i know how to deal with it.
I'm also thinking of remaking the starters.
So, what do you think?