Including event ribbons or past Gen ribbons, what is the highest amount of ribbons to get on a Pokémon?
If you don't transfer from other games you can get 5-6.
You can get 5 guaranteed Ribbons. Wild Pokemon have a chance to have a ribbon (I don't know numbers)
If you do transfer you can get 90 Ribbons.
Also check out Johnstone's video. He was crazy enough to do them all (excluding swsh because it wasn't out at the time)