Re: Aikido against judo
It's interesting to me that we tend to use the phrase, "Aikido" and "Aikido techniques" generically as if they are all the same. I have trained a little in enough styles to know that there are radical differences in how the techniques are executed and applied. I agree with Sensei George and would add the following.
1) It may be the type of Aikido that you are learning may not work well against judokas.
2) It may be that your personal Aikido isn't very good (for whatever reason).
3) Your own training in the dojo may not lend it self to defending against judo players.
4) You might need to reevaluate what Aikido is. My teacher says two things. 1) Aikido has no form. 2) There aren't any rules in Aikido (there are rules for practice and rules for the dojo but no rules for Aikido.) I recently asked him that if Aikido has no from, then what is waza? Waza are the means by which we learn and train in Aikido principles. Once we learn the principles, these are what manifests formlessly in a conflict and they adapt to whatever attack comes.
If you are trying to use Aikido techniques to defeat judoka, you may be going about this completely in the wrong way. Indeed, without understanding these ideas, you may have been training with a completely different outlook than for what it takes to engage in a conflict with someone of any martial art or even no martial art. It isn't judo players you need to worry about - it's everyone! Maybe you should go back to square one.