When it tries to evolve at level 45, press the B-button and prevent it. Every time it gains a level, it will try, so press the b-button and make it stop. When your Metang is level 53, don't interrupt it and it will evolve.
level it up to 45 and it will evolve
To get Metagross, make sure you have a Beldum. Then raise it so it can evolve into Metang. Then evolve it at level 45 but I rather make it evolve at level 50 because Metang can learn the move Meteor Mash then let it evolve into Metagross.
Yes, you can have a level 50 Metagross with Meteor Mash. you have to trade it to your Pokemon Diamond/Pearl/Platinum through Pal Park. Pal Park opens up after you receive the National Pokedex. (On your DS game...) It learns Meteor mash at level 55. However you can still make a metang not evolve (by pressing b during evolution or giving it an everstone.) and make it learn Meteor mash at level 50 and only let it evolve at 50 (it usually evolves at lv.40)and then you will have a metagross with Meteor mash at level 50.
In order to obtain Metagross, you'll have to complete the storyline and then head to Wintown. There, talk to Elita and she'll have a mission for you: you'll have to go to the Go-Rock Squad's hideout in the mountains. If you haven't done this already, you'll need two Pokemon with the cross ability - there are Tangela in the area. Go up the mountain and head in the direction of the Fiore Temple. In the area before that, you'll be able to go left after you climb up the steps with the falling Golem. Go across the waterfall with your two Tangela, and follow that path. Make it through the base, and it will explode. If you've already done that, then go back to the Go-Rock Squad's base, which should be destroyed. Make your way through it - don't worry about getting lost, there's only one path you can follow. At the very end, you'll find Metagross and two Beldum.
No to receive more beldums breed a metang or metagross with ditto. This is wrong. You can make Beldum eggs with any evolved form of Metagross. Don't forget to have a Pokemon that knows either Magma Armor or Flame Body to reduce the number of steps you take in half :D (Since Beldum takes a lot of steps to hatch).
Level it up to level 50, then it will evolve into Zweilous. Level it up to level 64, to evolve it into Hydreigon.
Staryu does not evolve by level. You use a water stone to make it evolve.
scyther doesn't evolve by level we will evolve if you make it hold a metel coat and trade it
You have to give it a certain item to make it evolve it doesn't evolve at a certain level
You can't evolve Pokemon in mystery dungeon games!
you have to trade it in the game to make it evolve
You have to trade it to make it evolve.