IVs and EVs don't exist in PMD.
All stat gains are set in stone for each Pokemon species, so e.g. all Bulbasaurs will always gain the same amount of stat boosts each level. I know this because I restarted a game once and the stat gains were the same.
You can boost your stats through gummies, health drinks, berries etc., but if none of those items are used, then your Pokemon's stats will be the same as the rest of its species.
Mystery Dungeon game mechanics - Bulbapedia