I have a trick thats really good.
If you name your self robert do the missingo trick and after you fight a couple of missingo's you will encounter a lv164 squirtle and if you keep on leveling him up with rare candy's he will get to about to lv250 and then go back to 0 if you lv him up too much. i have done it about a trillion times so it does work.

If you name yourself DzDzDzD you'll encounter lots of Mewtwos at level 185, and they don't know any damage-dealing attacks when you fight them so you don't have to worry about them being too strong for your party. Point?