Side Special - THIEF
The description of the move Thief states, "The user attacks and steals the target's held item simultaneously. It can't steal if the user holds an item."
So, like you see in that gif, Meowth pounces in one direction like
Side+B move. When Meowth lands on the opponent, he steals their held item and then jumps off them. If the items are turned off, well, Meowth can just meteor smash them straight down anyway.
One of the custom moves could be Snatch where Meowth doesn't steal generic items but he steals character unique items and effects of healing and stat-changing moves. Meowth can steal the effects of
deep breathing,
Monado Arts... Meowth can also pick up
bananas,
pocketed items,
vegetables,
bombs,
gyros, and even
Pikmin.