Hello, I saw the artworks of these megas and tried to redraw them the best as I could. Please don't spread this leak too much because I like my work and I don't want to get caught. Greninja has the least physical changes, but his tongue is now dark purple and he has overall darker colors with purple added to the mix. I think it's safe to assume that his mega is Water/Poison and he throws poisoned shurikens with his tongue. Mega Chesnaught is bulkier and fluffier, and he holds a shield in one hand and a mace that is his tail in the other. Delphox's mega looks quite predictable.