Stealtheon is level 43. It's defense attacks are 'steel shield' that lasts for 3 goes and mega-drain (sort of). It's attacks are shock-wave, shadow claw, mag field (electric blue field), iron tail, steely, hypnotize(paralize), maga(shield push), thunder-bolt. So it would definetally win!
To be honest, it depends on a number of factors. First, it depends on whether the Espeon or Stealtheon has higher attack power. Another factor is the moves they know. It would also depend on their defensive power. And then you factor in type advantages or disadvantages. So basically either could win. But then Stealtheon isn't a real Pokemon (Not yet, anyway.), so Epseon would aready sorta win. But let's just say this could happen anyway, either could win.
You probably already know this, but it's possible to defeat a Level 100 Arceus with a Level 1 Starly in only 2 moves.
