I didn't think it was fair of me to keep all these manga and animes that contain Gt to myself so here is everything I can possibly think of...
SPOILER ALERT FOR SOME OF THESE I GUESS!
7 senchi-Manga only.(Really funny! Recommended!)
Orichalcum reycal-Manga Only (Though it would be an awesome anime!)
Minimum <-WARNING ADULT CONTENT (lol then why am I reading it? t(ツ)_/¯ )-Manga only.
Fairial Garden-Manga Only (Cute!)
Midori Days-Manga/Anime (I recomend reading the manga of this one!!-though you will cry-)
Handmaid May- Anime only. (Gt for only halfway through though....)
Kaitou Drugers <-WARNING ADULT CONTENT! (But its a really sweet manga! ల(╯ಥ □ ಥ))╯ ) Manga only.
Fairy Cube (Haven't read this in ages but if I remember correctly, one of the main characters is a fairy) Manga only.
Shugo Chara (But im sure everyone has heard of this one!) Manga/Anime.
07 ghost (Reincarnated as a tiny creature, would that count? But as I said with dance in the vampire bund, this is an epic manga/anime seriously, watch/read it.)
Foo Fighter Fuji (I wish they did more of this!! X'C) Manga only.
Ginzatoushu to Kuro no yousei-( It has tiny fairies an stuff, not really for the weak hearted if you don't like fairies being bullied?)
(Oh gosh I'm going to say it...) Beserk- (WARNING WARNING WARNING!!!! IF YOU HAVE A WEAK STOMACH THEN DON'T READ! INTENSE GORE IN THIS ONE. Throughout the beggining-I had to stop reading half way through so I don't know if he stays a main character- one of the main characters is a fairy) Manga and I THINK there is also an anime? I'm not sure...
Sword art online- (A girl gets reincarnated as a fairy, cool anime, recomended- also the fairy manga version is: Sword Art Online-Fairy Dance)
The world god only knows (Shrinking only in the manga-> CHAPTER 43-44)
Pixie pop- Manga only (Contains a tiny fairy throughout the series. She grows for two pages in chapter 1 and shrinks in chapter 9(<-?))
Dong meng- Manga only.
Heartland no juunin-Manga only.
Project Doll-Phone- Manga only.
Chiisana Kyojin Microman- Manga/Anime
Kaze no Stigma-Manga/anime (It has a fairy character in it but she's kinda just supporting)
I guess these could be considered shrinking? Its age regression which is getting smaller soooooo....>.>
Mayonaka Lolita- Manga only. (Sweet manga! Wish they did more...)
Rakuen route-Manga only. (Cute!)
Dance in the vampire bund- (Even if you aren't a GT fan I still recommend this manga/anime it is AWESOME!!)
Kenketsu Rush- Manga only.
Lost Ikai no Kemonotachi- Manga only.
Mamotte lolipop- Anime/Manga.
NIL NO KOI MAHOUJIN- Manga only (This is cute >_<)
If you guys know some more please-please-please tell me, it'll be really interesting just to see how big Gt really is in manga and anime! Thank you and enjoy