Izakaya cover a wide array of different styles, from mainstream to Yakitori, Nikomi, places more close to a sushi bar or others specializing in raw chicken. However, there are some similarities: Izakaya food is simple, Izakaya food is fresh, Izakaya food is seasonal, and Izakaya food is usually cheap, at least it should be good value.
Besides the ubiquitous 枝豆 (edamame / green soy beens), standard fare at most Izakaya is fish in all variations, raw, grilled, fried, pickled, cooked (Uosan). Then there is 煮込み (nikomi / stew) (Tsutahachi, Kishidaya), also often found: potato salad (Saitō sakaba), 豚カツ (Tonkatsu) (Marumasuya) and 焼き鳥 (yakitori / grilled skewered chicken). Some dishes you will find only in summer like 冷や奴 (hiya yakkō / cold tofu), some only in winter like 煮凝り (nikogori / fish aspic).
A dish almost found everywhere and therefore very much suited for comparison is もろきゅう(morokyū), Japanese cucumber served with grained Moromi Miso. Here you will get a hint of how much effort the place puts into the quality of ingredients and presentation, refer to the pictures below, from uninspiring (left) and standard (center) to very enjoyable (right)
If you like to know more about izakaya food and recipes, I recommend to read “izakaya, THE JAPANESE PUB COOKBOOK” by Mark Robinson, and if you like to prepare Izakaya food by yourself: have a look on Norio’s very enjoyable blog.