I’ve done this many times but it’s just too risky! Rush down characters tend to advance toward him too quickly and leave very little space for the transformation. If I did transform, I’d have to REALLY hop and juke my way into clearing so I could set up a clean tagout. It’s too risky. Arthur’s assist without Golden Armor is still great.
What I do is, I try to maintain a lead against my opponent, THEN sub in Arthur as a keep away. By now, I should have enough hyper combo to turn him into Golden Armor and play “catch me if you can” (sort of, I do like to combo as well). But if he’s close to dying, I ALWAYS sub him out into 3rd position. He’s best as the last team member. So, if my other two teammates are dead, I hopefully have x factor ready while he’s in Golden Armor state with some HC guage to really get at my opponent.