For the most part yes. There will be a few situations where you need to take a specific mega pokemon or a NVE support pokemon but majority of the time optimizing should be fine.What level Pokemon should I have before tackling hard Lucario or special event Mew? I just started the iOS version and am not sure where I should be focusing my energies. I just hit optimize at the start of each level. Is that a good idea?
Lucario is probably best left until later and I don't think I had much trouble with Mew on 3ds. I would just continue focusing through the main stages until you get some stronger pokemon then go back to them when you feel ready.