Flavaquil - Yeah. That's basicly the last requirement to transform.
But also being that I thought about this for a VERY long time, I also thought of since Ash's reason for his transformation is anger and revenge (as to why you can all interpet for yourselfs), he might also unintentionally alienate his friends (Max, May, Dawn, Misty, Brock, etc). Because when one is in S.S. state, depending on how well trained the person is in controling such power, he can lose all sense of judgement for sheer emotional anger and emnity against the enemy. In other words, since Ash was NEVER a S.S. before in his life, the only thing he'll ever think about is getting revenge on the person(s) that etheir: killed his best friend Pikachu (no Pokemon can't die), or some other tragic circumstance WITHOUT the proper training to control his emotions.
But like I said it's been in my head for more than a while so... yeah.