Can you trade a Zekrom to Pokemon Soul Silver?

You can migrate SoulSilver Pokemon to the Pal Park in Pokemon Black/White, and then catch them, but you cannot trade them back, as Pokemon Soulsilver knows Generation's 1,2,3 and 4, but it does'nt know 5. Pokemon Black/White knows Generation's 1,2,3,4 and 5, so it can be a one way trade