Physical (252+/4/252) M-Charizard X stats at level 100:
HP: 297
ATK: 394
DEF: 259
SP.A: 266
SP.D: 206
SPD: 299
We can now imput these into a damage calculator—see pic related. I've added the strongest attacks available to WarGreymon in the game (you can see which skills it can learn here:
https://youtu.be/5wPR_APyquw?t=4m25s ), and used their Power values (taken from this guide:
http://www.gamefaqs.com/psp/637157-digimon-world-redigitize/faqs/71924 ) as their Base Power.
WarGreymon can learn Machine, Combat, and Fire attacks, so I've assigned them Steel, Fighting, and Fire type, and given WarGreymon STAB for each. Digimon World games of course have completely different damage calculations than Pokémon games, but let's just treat them as if they were Pokémon attacks.
WarGreymon (Magma Bomb) vs. 0 HP / 0 SpD Mega Charizard X: 181-213 (60.9 - 71.7%) -- guaranteed 2HKO
WarGreymon (Fighting Aura) vs. 0 HP / 0 SpD Mega Charizard X: 843-993 (283.8 - 334.3%) -- guaranteed OHKO
WarGreymon (DG Dimenison V2) vs. 0 HP / 0 SpD Mega Charizard X: 445-524 (149.8 - 176.4%) -- guaranteed OHKO
(It would be interesting to run calcs for contact moves like Mechanical Claw, taking into account its Dramon Killers which would negate the Steel resistance when used against a Dragon-type, but I can't be bothered right now.)
Now let's see how much damage Mega Charizard X can deal against WarGreymon:
252+ Atk Mega Charizard X Earthquake vs. Wargreymon [Steel/Fire]: 188-224 (3.4% - 4%) -- guaranteed 30HKO
252+ Atk Tough Claws Mega Charizard X Flare Blitz vs. Wargreymon [Steel/Fighting]: 222-264 (4% - 4.8%) -- guaranteed 25HKO
Not much, even given optimal typing. With a defensive nature and maximum HP/Sp.Def. investment, Charizard has a good chance to live through one of WarGreymon's strongest attacks, but it will lose on the next turn. Dragon Dance won't be enough to raise its speed above WarGreymon's, and even if it did, Roost doesn't heal enough in one turn to survive another attack.
