Where I live you can compete as many horses as you want.
There are places that you cant. There are non - federal venues that do not follow NF rules.
Hope your question was answered!
If any doubts, feel free to contact me.
In here you usually can ride up to 6 horses for competition (young horses excluded)!
Yes! I did for a few months, but i got stressed so i decided to only show one.
I have before in hunters, but I would check the shows rules before you do. If it is judged on the rider, like in eq, no, but if it is judged on the horse, like in hunters, I would say yes.
It should say in your federations rule book but usually yes you can