Notes on Monster types in Yu-Gi-Oh! vs. Pokémon types

1. Aqua, Fish, Sea Serpent: Water. Fish represents Water 2 Egg Group, while Sea Serpent is literally Sea Dragon, or Kairyu(Dragonite's Japanese name).
2. Beast, Beast-Warrior, Cyberse, Reptile: Normal-type. Beast-Warrior represents Human-Like/Field combination, while Reptile can represent Monster Egg Group at times. Cyberse is here because of Porygon.
3. Dinosaur, Rock: Rock-type. Dinosaur is represented by Fossilmons and Monster Egg Group.
4. Dragon, Wyrm: Dragon-type.
5. Fairy: Fairy, duh. Though Fairy in YGO is Angel-type in Japanese.
6. Fiend: Dark
7. Insect: Bug
8. Machine: Steel
9. Plant: Grass
10. Psychic, Spellcaster: Psychic
11. Pyro: Fire
12. Thunder: Electric
13. Warrior: Fighting
14. Winged Beast: Flying
15. Zombie: Ghost.

Notes:

1. Ice, Poison and Ground do not have direct counterparts. Earth is an attribute in YGO, not a Monster Type, so Beast can be the most fitting, but due to its abundance and variety it fits to Normal best. Ice is only a subcategory of aquatic types, and Reptile is only part of Poison-type in Pokémon.
2. Because most of the recent medium based and mystic based magical monsters in YGO tend to be in Psychic-type instead of Spellcaster, there isn't a true counterpart for Spellcaster in Pokémon.
3. Dinosaur also doesn't have a direct counterpart, but its Japanese name is kyouryu, which literally means "fear dragon" in its kanji (though it can also mean "strong lizard" in different kanji), a transliteration of the meaning of the name dinosaur in latin, which means "terrible lizard" or "potent lizard"). Similar thing goes for reptiles in Pokémon, but Poison and Normal is commonly associated with them.