I make okonomiyaki at least twice a month, my favorite type is the hiroshimayaki. Don't really need to over think too much.
My base batter is pretty easy, just dashi, eggs, flour, baking powder, salt, mirin, soy sauce. Make it a bit thicker as the cabbage shed water and make it thinner.
Add shrimp and squid if you want more depth of flavour. I like LOTS of green onions and the pork on top (see pictures) that way after you flip it, it cooks up crispy.
Carbon or cast iron both works really well, as mentioned earlier, lid helps steam the cabbage for faster cooking.
I dont like otafufu sauce ... I know I may be the odd one .... I make my own sauce, no cooking required: 1/2 cup Black Rice Vinegar and Maple syrup, 1tbp ketchup, hoi sin sauce and oyster sauce, dash of white pepper and sesame oil (not to much to over power), brush liberally on to okonomiyaki hot.
Oh and you want AO NORI, almost like the powder version of seaweed, this is the one thing I never have on hand.