The package is nice but not great sense in getting bogged down in text hacking and graphics hacking, though what you ask is actually quite hard. Most older games are not really AI as much as patterns, most older games do not abstract the patterns to an in game scripting engine so much either so you get to play at assembly level. For most then learning assembly is the last thing you do when learning the ropes as it is the hardest thing.
It might turn out that some aspects can be handled with a simple table in the ROM somewhere but you will want to put the spadework in to get there in the first place, and that will mean understanding what goes. In this case you picked a somewhat popular game franchise so you got lucky and someone has done much of the spadework already and shared it with the worldhttp://datacrystal.romhacking.net/wiki/Mega_Man_II:ROM_map#Boss_Behavior
It also says to me that most things are unique to each boss so if you want to go much outside the confines of the existing stuff, definitely if you want to make your own boss that is not a reskin and even then reskins can be hard if there are hitboxes involved, it is going to involve some learning.