Not really sure about any of this, but for 1986 it's most likely leafs. I've got a couple of complete conversion kits for games in released in 1989 and 1991 and they both came with leafs for both the joysticks and buttons. Now, these are Konami and not Romstar/Taito, and I'm not sure if the entire industry made the switch from leaf to micro at the same time, but if you can't get a solid answer one way or the other, then I'd think that going with leafs is a solid bet.
Looking at the instruction manual for Bubble Bobble linked at KLOV, it does mention that it comes with 2-way joysticks. Are you going to use 2-ways?
Rick