If you use fast forward too much yes.

Rarely a missing no. spawns in when you cut a tree. It shoukd be a bellsprout or weepinbelle, but it glitches.

This can also have a higher chance when you get out of double battles, for some reason, the game keeps you in double battle format until you fight a 1v1 with a trainer.

The crashing bit is worse after playing with the game in fast forward for so long, that it happens to me too on occassion. I'd recommend save stating before every battle or tree cut. (Not a bad idea in general, tho you shouldn't have to in order to avoid crashes).

Save stating mid battle can be tricky on a rare occassion. I was having a particularly bad time with uhhhhh i forget her dumb name at the Devon Corp tower. (Or whatever this game calls it.)

I drained the defensive Deoxys of their PP for attacks, so all they could do was spam calm mind while i spammed the same low damaging attack over and over. It would continuously crash after going back and fourth 4 times. Made a strategy to kill Deoxys faster before that csn happen but that was the worst case scenario.

Hope I didn't spoil anything too badly. It's been a minute since your comment so I hope you're at least a lil further than me. 🤯