Considering that there is a tag in this site named "licensing" and another named "copyright", I understand you bringing up such question to here before thinking of hiring a lawyer. But as the other two answers have already stressed, it's important to have it clear that most people here are probably not well equipped to give you the accurate technical answer you are looking for.
That said, if I understood your question correctly, you are thinking of using Pokemon characters for a school project. So, in similar situations when I was at university, it was frequent that people asked their institutions for counseling on that kind of matters. That is the first thing you should do. Educational institutions often have people with specific expertise on the specific law details related to the educational world - for instance copyright for educational uses and fair use (see more about fair use here, besides reading the basic wikipedia description).
In fact, there are often flexibilities when the use is purely educational - i.e. presenting a project in a class. However, the two important details are the meaning of what is "educational purpose" and whether you plan to take assets directly from the original source. For instance, posting online a learning game project, made for learning purposes, but which uses trademarked assets, not only is known to be a problem, but Nintendo has already fought that battle and took down a fan-made non-profit learning project: http://ca.ign.com/articles/2015/03/31/nintendo-takes-down-super-mario-64-hd-fan-project
But again, you should think of asking you own institution - specially because laws vary by country. Besides, maybe that is a fairly good question for https://law.stackexchange.com/. A similar question was already asked there, but from a Denmark-based poster and didn't got answers due to being non-specific. Maybe you can try it with further details there: https://law.stackexchange.com/questions/5226/use-material-without-permission-for-educational-purposes
Lastly, in case you feel unsure or get negative answers by your institution, what you can always do is try to simulate the combat system from Pokemon games but with your own characters and present it as such. It means, you can explain that you are going to present an application of the ideas behind how you understand the combat system and, for that, you are going to illustrate the problem using you own "creatures".