do still want all of these to be 16x16?

Ok, I think I could help you out a bit

Godzilla? sorry it's a little big. I couldn't get it much smaller with that detail

Might I request what that is ripped/scaled down/grayscaled from?  Unless you made a bigger version yourself, and then scaled down your own sprite, you really should give credit to the original author that you edited it from.  It's really frowned upon in the spriting/tiling community when you rip sprites and give no credit; ripping sprites, with credit, however is considered totally fine.

EDIT:

For a major thing that made me convinced this is ripped, or at least, scaled down by a major scale from a sprite of something at least 96*128, is the amount of grayscale shades in it; there's well over a hundred, from my painstaking color-replace count, which is a sure sign of this.  Correct me if I'm wrong, of course, and you can claim it for your own.

edit: and so you know if you look at any of my sprites, I use Jpeg compression all the time to get the color effects....I don't rip people off, as I have had that done to myself and I was VERY angry!

I understand that, I myself have gotten rather angry many times at the hands of sprite thieves, which is why I make sure challenge anything that doesn't look like original work, even if the original author potentially might not care.  As for a note of jpeg compression, I don't suggest it -- extra colors added during the compression process usually retract from the intended effect of a sprite; and honestly, with most sprites, I can genuinely say that usually 16 colors is a good number of colors for a large colored sprite; 32 colors is actually what many professional spritists go with today as a standard, as you can get some really nice effects from that.  Over that, from what I've seen, is really overkill.  I suggest you change to PNG compression.