He would still do 1 Damage, Although I think a Happiny using something pound would be weaker, but Your damage total rounds up.
If your Damage is 0.5 it round up to 1.
If you Damage is 0.5 and you got a Crit, it would double to 1.
In a situation like this, you might have a number like..
0.0002139827, and you'll round up, after your critical hit is calculated.