The SRU stands for cards that only come in foil right? I don't see SRU letters in cards that are SRU. Like Dragon Meleficent, I hear it's an SRU, but when I look at the Card it only says SR.

Super rare Unique is a term we use for SR cards that are only printed as SR. meaning their is no rare version of the SR.

Darkwing Duck said:

Mr. Duck has it. Super Rare Unquie (SRU), Super Rare Only (SRO), Super Rare Exclusive (SRE), and even Ultra Rare (it's used, by me, even though you still hold a 1/29 chances to pull any one Super Rare in set three.)

Just to Clear things, I won't see SRU on a card?

Nope, and if you did, then it will most likely be a misprint (unless they take up the name and start putting it on every card that is an SRU)