Ledian is a horrible Pokemon.
Johto has an unusually high amount of Trash Mons, from Sunflora to Bellossom to Aipom before Gen 4 to Unown.
Unown is still the worst Pokemon at battling in my opinion, but because it's a given and because this thread wants us to be creative, I will continue.
Ledian's stats are what screw it over. The only notable stats are its average Speed and its 110 Sp. Defense, and by the standards of the OR/AS power creep, that isn't even as impressive. 110 Sp. Defense also means nothing when you have no HP to back it up, a horrible defensive typing, and a 4x Stealth Rock weakness. Ledian still finds itself outspeed by a fair amount of things and because it has zero offenses, all it has been able to do in competitive is attempt to pull off extraordinarily niche Baton Pass and Dual Screen sets.
It's such a shame, because I really want to like Ledian. I'd love to use this thing viably, it's design is great. Ledian is not my pick for the worst Pokemon of all time. It has a good design and can at least try to pull something off in competitive. The biggest thing is just how disappointing it is. What are its stats? Why are these a thing? In a cruel twist of fate, Ledian got Air Slash, meaning Game Freak hasn't forgotten about it. This means that they actually think there's something worth not buffing Ledian for. It has no useful abilities, and if it does, its stats contradict them. Its typing is horrible and at this point, just a snore to see.
Ledian will tragically forever be eclipsed, and for that, I feel legitimate sorrow for the Five Star Pokemon.
In regards to what it isn't, I think Ledian is tragically one of the worst fully evolved Pokemon that evolves from an LC Pokemon. Ledyba isn't any better either.