Now, getting to the point of my question: At what point should I feed Mewtwo stat-boosting vitamins? Level 70? Level 99? (Because I know you can't use vitamins after level 99) Somewhere in between? Every 5 levels or so? I honestly don't know.
I tested it out with HP Ups and noticed that with each successive use the boosts got smaller and smaller; The first boost was +8 to HP, the second +4, the third +3 and every time after that was only +2 to HP.
Sorry if this has been asked a million times before, but I really don't feel like sifting through long FAQs/help topics regarding this.
The best time to feed the Vitamins to the pokemon is answered by:
1.) When you catch it or
2.) when you have it to feed it to pokemon.
(Because I know you can't use vitamins after level 99),
WRONG! Each vitamin gives the pokemon 10 Stat EXP in that stat, after there is 100 Stat EXP in that stat, the pokemon can't use any more vitamin in that stat. So you can Rare Candy a pokemon to level 100 then feed it 10 of each vitamin.
Honestly, it doesn't matter when you give the pokemon a vitamin. So long as you max out the Stat Exp, the stats will be the same no matter what (depending on the EV's, of course).