The wall of bricks!!

*sigh* Fine, including that in random number generator thing.

Of course, if you post no number, I won't apply any damage at all!

I choose 51. Also, every time you post, a turn goes by, even if no one makes moves. Therefore you lose HP every turn. You better throw this in, too;

Walrein uses Toxic on the wall. 85% accuracy normally, but with No Guard, it can't miss.

Toxic

Inflicts intensifying poison on the target. This does damage equal to max(floor(max HP/16), 1) * min(# of turns Pokemon has taken Toxic damage, 15). This has the effect of doing 1/16 max HP damage the first turn, 2/16 max HP on the second turn, then 3/16 on the third, etc., adding 1/16 to the damage each turn. It maxes out at 15/16 max HP damage.