>>12240285No, his/her/its health is based on his/her/its health stat, with the max being 100 (Or maybe 200), and the min being 1
The way it would work is that it takes a percentage of (one of) the other pokemon based on Substitute's HP stat, so say that the other Pokemon has 200 HP, and Substitute has an HP stat of 2, Substitute would have 2% of 200 for his/her/its HP, or 4 HP.