404 HP (52 EVs) is enough to create 101-subs. It may not mash up with the Leftovers recovery, but you can create a good amount of subs once you at least get one free turn. At least when there is no need to substitute in extreme conditions (sandstorm); in that case you have to creep over the next sixteenth. With 104 EVs KyuBey reaches 417, enough to sub higher than 100 and to push your HP to your limits in any situation. On the other side, I doubt there would be a wall who would voluntarily stay in one of the best wallbreaker in this tier.