Are you on crack lol wait till i find some of the conan comics i got when he's a king the dude is inventing weapons, devices and using insane tactics against giant monsters and rival armies that Leonidas could only dream about.
All Leonidas did was have the common sense to realise that by digging his men into the hot gates pass they would be able to survive while the army flooded into they would contiunally be able to make a dent into the ranks. It's not that hard to fight with your back against the wall when you got some skilled help.
Conan. He's bigger,stronger and I'm not too sure if Leonidas is any faster. Conan did beat Captain America in a What If story (if that counts for anything).