APOL, 35 bytes
j(ƒ(i ¿(&(c(Ⓔ ↓(∋)) ≐(∈)) ∋ ↑(∋))))
Explanation
j( Join a list to a string
ƒ( Listbuilder for
i Input
¿( Returning if (called for each item in the input)
&( And (condition()
c( String contains
Ⓔ The constant string "aeiou"
↓( To lowercase
∋ Current character
)
)
≐( Is even
∈ For loop counter
)
)
∋ For loop item (executed if true)
↑( To uppercase
∋ For loop item
)
)
)
)