Yes, the two of them are in the Amorphous Egg group, so they can mate with each other.
Shuppet evolves
Shuppet evolves at level 37
Shuppet is a Ghost type pokemon.
Shuppet evolves into Banette at level 37.
Pokémon that can breed with Ralts are Muk, Gengar, Haunter, Weezing, Wobbuffet, Slugma, Gardevoir, Kirlia, Swalot, Shuppet, Banette, Dusclops, Drifloon, Drifblim, Spiritomb, Misdreavus, Mismagius, Gallade, Dusknoir, Duoosio, Reuniclus, Jellicent, Tynamo, Lampent, Pumpkaboo, Chandelure, Gourgeist, Castform, Gastrodon, Cofagrigus, Phantump, Stunfisk and Trevenant.
Shuppet evolves
Shuppet evolves at level 37
Shuppet is a Ghost type pokemon.
Shuppet evolves into Banette at level 37.
Shuppet will evolve into Banette at level 37.
Shuppet evolves into Banette at level 37.
There are no Shuppet eggs in Pokemon Diamond.
Pokémon that can breed with Ralts are Muk, Gengar, Haunter, Weezing, Wobbuffet, Slugma, Gardevoir, Kirlia, Swalot, Shuppet, Banette, Dusclops, Drifloon, Drifblim, Spiritomb, Misdreavus, Mismagius, Gallade, Dusknoir, Duoosio, Reuniclus, Jellicent, Tynamo, Lampent, Pumpkaboo, Chandelure, Gourgeist, Castform, Gastrodon, Cofagrigus, Phantump, Stunfisk and Trevenant.
Shuppet evolves at level 37 into Banette.
It evolves into Banette. It's a Ghost type Pokemon, pre-evolution of Shuppet. Shuppet evolves into Banette at level 37.
In what game? check out serebii.net and you can find out where to find shuppet in every game.
Shuppet is #353 in the national pokedex, and it is a Ghost type Pokemon.