Hi, this isn't too bad at all dude.
I think though for a sumo wrestler your guy looks a bit too muscular, whereas sumo's tend to appear more flabby/fat. I think your guy looks more like a big strong guy rather then a sumo, so adding in some details such as the stump of hair (no idea what its called) at the top of his head, perhaps making the loincloth (or whatever it's called.. oh boy have I offended this martial art yet?, my bad) to make it look more like the ceremonial ones they wear. .. regarding his pose I think the pose could also be more iconic to a sumo were his hands are leaning on his lap, in a similar way to a Maori dance, kinda sorta, not.
Anyway I did not get much time to mess with this, so its quite unfinished with shading in particular ,perhaps you or someone can continue with it. I was mainly trying to demonstrate the pose... I also think a combination of out stretched arm and the tucked in one looks good and you could imagine it being animated like that.
Well done with it, the piece itself in my non-expert or professional opinion is certainly beyond total beginner, I would say above average. If you are asking what your personal level is at, well I guess that would come down to consistency with many works so I cannot comment other then to say you certainly have potential by the looks of this piece.