If there are competing "gain" or "loss" effects, the most recent effects is applied. For example, if Loup-Garou is played while an opponent has a "Fina, the Silver Player" on the field, its gain effect will override Fina's loss effect. However, if Fina is played after Loup-Garou is already on the field, Fina's loss effect will override Loup-Garou's gain effect.
A "Moon" is an addition subtype. This card does not refer to cards with the name "Moon" in them.