>>33704680A mega is +100 to the bst of a mon and usually a helpful new ability at the cost of an item slot and the ability to use another meta.
Ash greninja gets +110 to its bst, you can use a mega with it, and base greninja is strong and fast enough to get a kill to activate it.
The only real flaw is no ability, but it trades that for the ability to use an item.
It's arguably better than a mega.
