My friend had both of the magestic dawn leafeons in his deck, he doesn't have the lvl X but since I ruin a water deck he has come back from me having only 1 prize left with him having to winning the match
Gee, that's great. How about actually rating the cards?
Leafeon LV.42, first, is definitely superior. 90HP is good, Bind Down ensures you can get at least 90 damage in with both attacks, and Leaf Guard can save Leafeon's skin at precious times. All that for {G}{C}{C} is also great. Weakness can't be helped, Resistance is nice, and whilst the Retreat Cost is iffy, it's the same for the LV.X anyway.
Leafeon LV.40 isn't so good, and it's fairly obvious as to why this one was chosen for the Leafeon theme deck - it's generic. Attacks aren't too bad, admittedly, and the retreat cost is better, but if you run the LV.X (which you should, if you run Leafeon), you're just gonna end up with a CC retreat cost anyway.
Leafeon LV.X...wow. First of all, great that it doesn't have a x2 weakness, even though it can still easily be OHKO'd. The thing is, the Poké-Power and attack are what makes this card special. It is, undoubtedly, a very scary card. Put it together with Umbreon (zero retreat and no weakness for all -eons) and Togekiss (Poké-Power, yes please) and you've got something that even the toughest of Fire-type decks, or any type for that matter, is gonna have a feat taking down.
Leafeon LV.42: 8/10
Leafeon LV.40: 6/10
Leafeon LV.X: 9.5/10