For single player game - do invalid encountered Pokemon actually break the game?

[monochameleon]

Hi. This is a question that I am trying to find a straight answer to without much success. Basically, I want to fiddle a little with the games to give myself a few Pokemon early on - I want to try using a Ponyta or Tauros from near the start of FireRed, for instance, or give myself all three starters as their OT in Diamond. My question is this: as long as I don't give them illegal moves, or bring in Pokemon from outside the region I'm playing in, will the fact that the encounters are showing up as invalid in PkHex actually cause me problems? I'm not going to be using these Pokemon for anything competitive, just playing through the game in a new way, basically. So, my question is: is this likely to break my game, or will the game not care too much?

Any and all help is greatly appreciated.

[theSLAYER]

In most instances, no. Unless it’s something so bad that the game alright refuses to load, they typically load Pokémon structures just fine.

[monochameleon]

@theSLAYER, thank you very much for your help.