Cheat engine hex codes for droppable summons.

[Kasu]

B7 08 - goblin
B8 08 - bomb
B9 08 - cockatrice
BA 08 - mindflayer

Don't know how cheat engine works? Read this: https://steamcommunity.com/sharedfiles/filedetails/?id=363028841 but do note that the memory addresses are different between FFIV and FFIV:TAY. For example the hex code for potion is 9E 08 XX 00. Replace XX with the amount of potions you have in your inventory.

[Kasu]

Some other things, including adamantites, tails and other missables.
chocobo - 94 09
Silver Apple - B0 08
Soma Drop - B1 08
Fuma Shuriken - 11 08
Lunar Curtain - 95 08
Unicorn Horn - 9D 08
Adamantite - C7 08
Elixir - A3 08
Queen's Whip - 50 09
Pink Tail - C9 08
Blue Tail - 27 09
Green Tail - 3C 09
Red Tail - 47 09
Black Tail - 4B 09
Purple Tail - 5E 09
White Tail - 68 09
Gold Tail - 79 09
Gray Tail - 85 09
Ebony Tail - 8B 09
Rainbow Tail - 9D 09
Small Tail - 99 09