[quote=@Nimda]
<Snipped quote by Yatagarasu>

Is that the strongest form of that attack?
[/quote]

The Rasenshuriken is among the strongest wind techniques there is, but you can make a form of it with each release nature, to varying effect. Technically you could make it stronger by combining it with a Tailed Beast Bomb, which we'll be covering later. But yes, in general, the Rasenshuriken is the strongest form of the Rasengan.