Wall for AnotherLeviathan

This isn't going off of your rules, but I did a realistic Pokemon team thing before, here's how that went:

"My REALISTIC Pokemon team:

1. Pidgey/murkrow
2. Skwovet
3. Treecko
4. Trevenant
5. Turtwig
6. Rotom Mow

Pidgey/murkrow - just some common bird, although I have found some crow or raven feathers so likely murkrow. Realistically, I wouldn't be beating up the common bird for exp or stumble across a Dusk Stone so I don't think I'm getting the evolutions.
Skwovet - a common squirrel. So many squirrels around. So many dead ones...
Treecko - I've seen a fair share of lizards around my house.
Trevenant - one night it was so stormy a tree behind my house fell over. So free trevenant. Plus I'm not finding a dead child to stuff in a tree stump for the pre Evo and also I play with sticks a lot.
Turtwig - Almost killing turtles thrice in the backyard with a lawn mower at least warrants a turtle Pokemon.
Rotom Mow - the lawn mower from the previous entry.

Some alternatives for the last one if I don't stumble upon a rotom are ekans (I found a snake once), a fox Pokemon (I saw a fox once), rattata (we had rats once), buneary, deerling, some bug type, or if you want to get real creative a small plane crashed next door and burned the house down some years ago so latios with a flame orb."

Are frogs leviathans?
If so join team ribbit

If you are another leviathan, then which leviathan are as opposed to the leviathan that you aren’t?

For your reference: https://pokemondb.net/pokebase/meta/83103/irl-regional-differences-of-games