o.k Apoc can grow and us his atomic altering ablities to make himself a dense metal alloy which can't be harmed. Apoc could then use his powers to increase his size..thus increasing his strenght.
A-kick Doomsday off the planet
B-punch Doomsday into a lake.
C-hurl Doomsday into a ocean
D-throw Doomsday into a volcane
E-toss Doomsday onto the moon
F-punch Doomsday into the sun
G-project Doomsday into a river
H-or just stomp on Doomsday until he wakes up in China.