I did some looking and I did not find any relatives of Stegosaurus with plates but no tail spikes. The tail spikes, or thagomizers, were used as weapons for self defense against predators.
Stegosaurus had 17 bony plates that were embedded in its back. The plates ran along the Stegosaurus' back and tail in two rows, and the plates alternated in alignment. The largest of these triangular plates was about 2.5 ft tall and just as long. Stegosaurus also had spikes at the end of its flexible tail.
There are no animals today that look anything like Stegosaurus. If there were, it might be easier to determine what Stegosaurus's plates were used for.
AbaRed's dinosaur form looks like a red tyrannosaurus. AbaBlue's dinosaur form looks like a blue triceratops. AbaYellow's dinosaur form looks like a yellow pteranodon. AbaBlack's dinosaur form looks like a black brachiosaurus. AbaKiller's dinosaur form looks like a white tupuxuara.
Depends very much on whether is "looks like" a dinosaur egg or IS a dinosaur egg. A dinosaur egg, after all, looks quite a bit like a rock.
Kentrosaurus (it looks like Stegosaurus)
it is called glalie
A meat tenderizer looks like a hammer but with small spikes on the end.
ceratosaur
I think it's a hedgedog.
A uromastyx is a lizard with a spiky tail, a flattened body, and a robust build. They have scales in various shades of brown, yellow, orange, or red, and some species may have patterns or markings. Their heads are slightly triangular and they have round, protruding eyes.
A mace looks like a handle that has a chain and at the top there is a ball thus with spikes
A chickawaka is a prestriomic time creature. It looks like a chicken/ dog/ dinosaur.