The strongest, if Ashley had to fight his way out, is tough to say because of Ashley's typing. Nuclear is weak to everything, but super effective against everything except Steel. If Ashley was against something that can potentially take one super effective hit, then he'll be in trouble. If he's against any Steel or part Steel Pokemon, that puts him in a worse spot because he doesn't have the advantage anymore. And even though his ability makes the strong Normal-type moves he can learn into Nuclear, he can't reliably fight his way out if the opponent is part Steel. And seeing as a lot of Pokemon are dual types, it's hard to say what would be considered the strongest one for him to face because he's aiming to quickly end the fight because of his glass cannon typing
