The copies will always be a huge 7/5 body, and that complements strong combat abilities like lifelink or double strike
The high attack clause is the most self-explanatory, you want a high attack monster so you can easily attack for game, there are plenty of more powerful monster that you could run instead of Dragulas, such as Number 77: The Seven Sins, having 4000 ATK, but it doesnt meet all the other conditions
Gladiator Beast Dimacari X EARTH Level 4 [ Beast / Effect ] ATK 1600 DEF 1200 If this card was Special Summoned by the effect of a "Gladiator Beast" monster, it can attack twice during each Battle Phase
Fortress Whale NO PASS 328
Theres also a card divider matching the colour of your chosen deck box included too, which can be a pretty useful thing to have when organising your cards
What is the rarest Pikachu card