It evolves to Metang at level 20. Then, Metang evolves to Metagross at level 45.
Train it to level 20
Beldum evolves at Level 20.
Beldum evolves at level 36.
Get Beldum in the Massoutbreak evovle @ level 20 and into Metagross @ level 45
Beldum evolves at level 20. It turns into a Metang, which will evolve into a Metagross at level 45.
Level 33.
it evolve on level twenty two in emerald
Beldum evolve into Metang at lv20 and Metang evolve into Metgross at lv45
at level 20
Lv. 20 into matang
Train a Beldum to level 33 then train Metang to level 50 to get Metagross.
Lvl 20. I recomment serebii.net for Pokémon evolutions and where to find them. Just search your pokémon + serebii.