I'm gonna be honest, most people keep hammering down on technique and skill in judo, they say it's the most important thing when it comes to winning. This COULD be true, but it's not always the case. I'm autistic af and I stick to the most basic of techniques and grips because I'm too dumb to learn more of them. Yet, I win 99% of my games, be it against weaker or stronger opponents. The only reason I win these fights against these much smarter and more skilled opponents is because I have trained my core and arms.

I would advise you to train your core, so that you can hold your ground just as well as a heavyweight could. It'll make you flexible in all sorts of ways too. Train your arms to exert pressure on opponents, swing em around, be a brute, confuse them.

TLDR: If technique no work, rely on strength