Magneton is made from three Magnemites. Metagross is made from two Metangs, and Metang is made from two Beldums So are there any more Pokemon like that?
One of DODUO's 2 heads splits to form a unique species. It's made from one of Doduo's head.
It is called “The Walking Jungle.” If a head grows too big, it falls off and becomes an EXEGGCUTE This means Exeggutor made from three Exeggcute.
Where two kinds of poison gases meet, 2 KOFFINGs can fuse into a WEEZING over many years. Weezing is two Koffing.
It is said that if an ONIX lives for over 100 years, its composition changes to become diamond-like.
Steelix is an Onix. 9. Metagross and Metang: Two Metang and two Beldum. 10. Combee: According to its Pokédex, > A Pokémon formed by three others.
Vanilluxe: According to its Pokédex, > Vanilluxe is born when two Vanillish, half-melted by the day’s light, stick to each other and freeze together in the cold return of night.
Amoonguss: Its name means "A foongus among us". This means Amoonguss has a Foongus.
Klinklang: although it's not mentioned it's a Klang or Klink anywhere, it looks like a Klang and Klink.
Hydreigon and Zweilous: Again, it's not mentioned they are a Deino, they look like three and two deino.
Diancie: Its pokedex says, > A sudden transformation of Carbink, its pink, glimmering body is said to be the loveliest sight in the whole world.
Barbacle: Its Omega Ruby Pokédex, > When they evolve, two Binacle multiply into seven. They fight with the power of seven Binacle.
Sorry if I have missed anything.