1. People think Togepy
evolves into Chansey. Well, I have proof that Togepy doesn't, because Togepy
evolves into Togechikko!
2.You can't get Mew on a gameboy for now. I think you can get it in the gold/silver versions. But for now you you have to trade with someone who has a Gameshark of use your own Gameshark.
3. It is impossible
to get Pokemon whose number is higher than 151 on pokemon blue/red/yellow.
You can't because the Pokemon's data wasn't made in the game. You can only
get them on the gold/silver versions.