What is a Monster Enhancer for the purposes of Mate?

[Munchk]

While playing my friends and I encountered an argument that hopefully you guys can resolve.
While facing a monster my friend (who had tons of bonuses on him) was winning, so to stop him from winning my other friend put an item card that boosted the monster that allowed 3 to either side(chose the side to enhance the monster of course) and a different card that did plus 5 to the monster.

The friend facing the monster was still winning, however this time a different person threw down Mate (which states: Another monster appears, of the same Level and with all the same Monster Enhancers....)

Now this is where I need help. What constitutes as a Monster Enhancer?

Are Monster Enhancer cards only the ones that say +5,+10,-5 at the top of the card?

Are Item cards considered Monster Enhancers? (The ones that say 3 or five to either side)
Example: Potion. Will this count as a monster enhancer card even though it is not specifically for monsters?

I guess what my general question is, what specifically is a monster enhancer card? is it only the cards that say plus to monster at the top? or can they be treasure cards?


Thank you guys for taking the time to reading this and helping me out