My one problem with this is I see no good explainations to half the theories out there right now.
I see fighting suggested a ton for pokemon and see no way they'd ever become fighting without SERIOUS redesigns. These are more pallet swaps with some details edited. Executor got a neck and a tail, ninetails and vulpix are a bit more fluffy (rather than a smooth sleek coat) and white, sandshrew has a bit more thickness and is white sandslash got ice spikes.
That said pokemon i think could get a whole new form with that limit (pallet swap 2-3 tiny detail changes):
Krookodile line: Water Dark or Water Ground pallet swap to a dark swampy green, change the back spines a little, and give it vertical instead of horizontal stripes.
Rhyperior line: add some fire vents and make them much darker tada you have a rock fire type.
Scyther: Bug Dark, make it darker, straighten the scythes to more of a tanto blade, and boom ninja bug pokemon that I'd use far more than ninjask.
Politoed: Water poison, color him like a poison dart frog all is good.
Garbodor: poison steel, remake basically entirely into a scrap heap junkyard golem creature that is actually cool and terrifying.