Bowser has lead with it once. Bowser's leading tactics change in almost every showing. In Super Mario Bros, he lead with hammers. In Super Mario Bros 3, he lead with Ground Pounds. In Super Mario World, he leads in his clown cruiser. In Paper Mario, he leads with Plot Manipulation and Sealing at the beginning of the game, toying around and Invulnerability/Fire combo with his second battle, Invulnerability/Lightning/Energy Projection/Fire in his final battle, in TTYD, he lead with just basic melee, in Sticker Star, he lead with trying to be sneaky, and then Reality Warping, and later in the game lead with Reality Warping and Summoning and Size Manipulation, in Colour Splash, he lead with Black Paint attacks, albeit, he was possessed, in Odyssey he lead with throwing his hat at the opponent, in SM64, he leads with Fire and Earthquakes, in Dream Team, he lead with Reality Warping(he was empowered by the Dream Stone, yes, but it's still a battle tactic), in Dance Dance Revolution he lead with Death Manipulation and Transmutation, and he also lead with Transmutation at the beginning of Super Mario Bros against the Toads, in the manga, he employs a new strategy in almost every fight(I know we don't really use the manga for him, but it's valid to the point I'm making, especially since the manga is based off of the games)...
The point I'm making is that Bowser can start with nearly any of his abilities, and Plot Manipulation and Sealing are not out of the range of possibilities to use. For this reason, I'm voting Bowser.