Stakes Winner 2 is bilingual. From the title screen, if you select the first option, it plays the "domestic arcade mode" (i.e. the Japanese version) but if you select the second option, it's the "international arcade mode"!
Then you'll get English in much of the game, including name entry, horse names and stats, and in-race text. Unfortunately, the tips after you lose remain in Japanese (thanks to Malenko for pointing this out to me).
The third option on the title screen is "original mode" and the fourth option is "option," and both of those are still in Japanese.
Also, sadly, Stakes Winner 1 doesn't seem to have an English localization included. Its title screen is in English, but everything after that is in Japanese, with no "international version" option readily apparent.
BTW, in case you were wondering, the Option Menu's first setting is for sound, with stereo being on the left and mono being on the right. The second setting is difficulty — left is easy, middle is medium and right is hard. The third thing you can select is key config — setting up your controller buttons, in other words.