I was bored a while ago and Then this idea came to mind
This funny little guy is based on a few things like other missingno appearances and ??? From Gen 3
I’d give this guy the Rock/flying type
And as for pokedex entry:
“With an unknown origin, Delta MISSINGNO is an enigma. It’s thought that a rare case of cosmic rays hitting a computer led to the creation of this Pokémon.”