Notes:

These are fakemon I designed to evolve from Ledian and Ariados. Lediva evolves from Ledian by leveling up while holding a Fire Gem; Arachion evolves from Ariados by leveling up while holding a Ghost Gem. Lediva takes Ledian's stats to the next level, boasting a stupidly high Special Defense (base 200), while improving the rest of its stats. Sadly, its stats other than Special Defense are still relatively mediocre. Arachion, stat-wise, is basically Infernape, only it's slightly faster, stronger, and frailer. However, both Lediva and Arachion have Zen Mode as their Hidden Ability, causing their stat spreads and typings to change at under 50% HP. Lediva becomes Bug/Fire and trades in some of its Special Defense and Attack for an enormous boost to Special Attack and smaller boosts to Speed and Defense. Arachion becomes Bug/Ghost and trades in some of what little Defense and Special Defense it has for small boosts to Attack and Special Attack and a gigantic boost to Speed – to wit, Zen Mode Arachion is faster than Speed Forme Deoxys with a titanic Base 200 Speed. Both are very strong Pokémon and huge improvements over their pre-evolutions with or without Zen Mode.