Biko Bold is also a good alternative.

I didn't found the real font but I found "P22 Underground Demi" which is a bit similar.

Lovelo for "Unconditionally" ?

It's Arial Black (the "c" straight lines aren't horizontal like in Helvetica)

"ITC Avant Garde Gothic" maybe ?
But the "E" are longer...

The second font is not Century Gothic but "Sackers Heavy Gothic".
For "VERONICA ROTH", it's written in uppercase and for "one choice can transform you", it's in lowercase.

Merci beaucoup =)

Thanks

League Gothic

Knockout

Intro / Intro Inline

Not the same but similar : Cashback Light

Some official images are using "House Paint" but I think "Midnight Memories" is not a font. (I'm French)

Look here : http://www.dafont.com/forum/read/156118/katy-perry-new-font

Probably an adaptation of "Tungsten Bold", which is used on her official website. It's a commercial font. (Sorry, I'm French...)

It's "Arial Black", not "Helvetica", because of the tilted lines in the "a", the "e", the "c"...
Sorry for my bad English, I'm French...