pokeLOVE: To shrink down a banner, the total pixel needs to be 46800. You can always find the resolution of your banner then use basic multiplication to see whether or not it's 46800 pixels or under.
diablo_200525: You're fine.
chupicabra: You're fine.
Alder: You have 3 outside images. Delete one.
Chibi_Poke: The banner is way too big. Also, you need to put credit(s) if you didn't make it yourself.
TyranitarFan: You're barely fine. It's okay for now.
riolulu: You're fine.