What I am asking is when someone says it goes up 1 level is that the same as multiplying it by 1.5 and is 2 levels the same as multiplying by 2?

2/8
2/7
2/6
2/5
2/4
2/3
2/2
3/2
4/2
5/2
6/2
7/2
8/2

and everything starts out at 2/2. These are multipliers, so Agility would move your speed (there's one for each stat) two spots up to 4/2, or double your original speed. Likewise, Cotton Spore would lower your speed down to 2/4 from 2/2. For a move like Sharpen, it just moves one spot up, so your attack would just be at 3/2 from 2/2. Belly Drum, although your own guy takes damage, would raise your attack up to 8/2 if your attack is above 2/6. (at 2/7 it would be raised to 7/2, and at 2/8 it would be raised to 6/2).

Curse raises up Attack and Defense (if it was at 2/2 it would become 3/2), but lowers your own speed (instead of 2/2 it would be 2/3.

This is the reason why you should get your stats all the way up and the other guy's all the way down. If you critical, you would deal 32 times the damage of a normal hit with all the relevant stats at 2/2.