Tidus can't realise the stress that Romeo is putting himself under, but he's doing as he says, building up the spell and then hurrying to release it with as he throws out a hand. "Get lost!"

And from where they are, water builds up quickly into a large sphere, catching individual pieces of their bodies but more focused around one. They can move, but it happens in seconds: water forming and then bursting out, knocking the wolves back and off their feet.

He can give more where that came from too, in smaller spells, another quick wave of his hand knocking downwards causing a gush of water to erupt upwards. Get the idea, dumb dogs!