I thought that I had commented in this thread, but it must have been another discussion.So what you are saying is that to get working aikido take a sumo lesson?
I'd say that Sumo competition is actually an ideal opportunity for testing and applying Aiki principles. The reason is that Sumo incentivizes charging and attacking with 100% commitment. (Including attacks that would be considered overcommitted in other contexts.) This is because you can win a match in seconds by blasting your opponent out of the relatively small ring before they can respond.
This full-body commitment of forward energy gives the other wrestler opportunities to blend with the charge, evade, and send the charging wrestler flying. But only if it's done with perfect awareness, timing, and balance. Otherwise the wrestler who is moving forward can just adjust their trajectory and easily overwhelm the wrestler who is trying to evade.
In most other forms of grappling (Judo, BJJ, wrestling, etc) competitors will not usually give that degree of forward commitment and so will not offer the same opportunities for displaying pure Aiki blending.