>>37972970>>37972993>>37973273>>37973411Plants also respire aerobically. During the day they'll often use the oxygen they've produced through photosynthesis, but it's most obvious during the night since there's no sunlight to work photosynthesis at all, and they instead use oxygen in the atmosphere and produce carbon dioxide in respiration like animals do. This also occurs in young plants that are still sprouting and thus not out of the ground, or in marine plants or parts of a plant root that are deep enough to have limited access to sunlight. In all of those cases photosynthesis is either not an option or extremely inefficient.
The balance is usually skewed towards producing more O2 than using it, but that's dependant on temperature, sunlight accessibility, CO2 availability, etc. At worst a sleeping grass-type would reduce available oxygen overnight by a fraction, but it'd be much less significant than having any other Pokemon near you, and would make up for it during the day.
A single human breathing on them wouldn't have enough of an effect to cause any noticeable change in growth, at least not in the short-term. Maybe a large group of people in an isolated room with one grass-type would have an effect though.
I'm not saying double-teaming your Lilligant would make her grow faster than just the two of you alone, *but*...
