What the lions have:
Majority and a bunch of Disney songs
What the pokemon have:
1 of every mon can take out a billion lions with Hakuna Matata, 'It means no worries!'
- LC pokemon are generally weak but they can still take out a bunchwith perish song; Azurill, Cubone, Igglibuff, Popplio, Smoochum, Swablu. These pokemon can just go to some high place or lower (whether carried by a flying pokemon, an unfamiliar terrain or further water in general).
- Trap setting in general; Do lions have rapid spin or defog? Not really. How would they deal with an unfamiliar stealth rock, spikes or toxic spikes. Any pokemon that can set up its surroundings with these can easily weaken its lion enemies and considering they aren't pokemon, their weakness to it is much more. They'll easily take way more damage leading into their defeat if they even reach the pokemon they are up against.
- Stats; Pokemon can just... Belly Drum, Swords Dance, Nasty Plot, Iron Defence, Calm mind, Tail Glow, Cotton Guard, Coil, Quiver Dance, Geomancy, Shift gear, too many to mention them all. Any defence, attack, speed or special attack practically outdoes the lions. With the amount of pokemon getting these moves, there's no way the lions could even scratch them.
- Effectiveness; The best a lion can do is bite or scratch. For one, rock/steel types are generally too tough for the lions to provide any effect. They ren't the best of swimmers to water types can just sit in water while using surf, hydro cannon and so many other moves with an almost guaranteed unstoppable force. Can they even hit flying types - they are on the ground and are stuck grounded, flying or levitating immediately have an upper undefeatable hand. Theres literally like over 35 mons that can have levitate, not mentioning the flying types that can fly. Special attackers too here have the upper hand from such range by not having to get up close to decimate the lion population.
Status; Lions can't cure status, highly spread burns, paralysis, freeze, poison and theoretically sleep effect the games features and technically aren't natural and therefore are probably unrecoverable. Most pokemon have a way to spread status and thats pretty much an ultimate blockade.
- Some specific pokemon;
In the rare case that all pokemon are defeated - Yveltal; is practically unstoppable. If it gets taken out it'll just take out and then wait there for another batch of lions to attack repeating the cycle no matter what comes. Therefore, in the long run 1 of each pokemon would win guaranteed.
Excadrill with any sandtream setter; Excadrill has earthquake. And it has sand force or sand rush. Lets think logically here. Earthquakes in real life are extremely destructive natural forces.. That with excadrills abilities... is there anything else to say?
Dynamax; Dynamax in the case that the pokemon that is Dynamaxed can attack only one pokemon at a time - but this is versing a billion lions, they don't have the rules of pokemon on them. A Dynamax blow would literally destroy the lions. The highly increased size along with the max moves, and what are a bunch of small lions going to do to something like snorlax, give it a free nail trim? Yeah definitely something that shows a billion lions still stand no chance against even singular pokemon sometimes.
And then there's one more thing I guess; If you're thinking there is no way that the pokemon could defeat all the lions in their lifespan *cough* *cough*, oh look:
Yeah so that. Infinite pokemon that contain all the points above depending on the criteria. Pokemon win, gg