ニンフィアとリーフィア
リフィグレも好きだけどこのコンビも好き

Sylveon and Leafeon
I like the Leafeon/Glaceon combo too, but I like this combo as well

<tn> These two are referred to as the "fia duo" here because in Japanese, Sylveon and Leafeon are Nymphia and Leafia respectively, and are the only Eeveelutions whose names end in the "fia", unlike their English names which all end in "eon".</tn>