Teal Mask Ogerpon ex only attaches energy to itself, Hydrapple ex attaches energy to anything. Syrup Storm scales with energy anywhere on your board instead of just actives.
i can't believe i'm about to yap this hard about a childrens card game ... my bad lol
this might sound nice on first impression but the reality is that it's a stage 2 pokemon, and that severely hampers its ability to be effective.
it's historically very difficult to get multiple stage 2 pokemon onto your board. needing to find multiple rare candy combos, while putting yourself at the risk of tm devolution, means that at best you're able to typically have a board state of two stage 2 mons.
that's why hydrapple's ability is not worth it at all. only accelerating one extra energy is absolutely limiting, and is strictly inferior to every other viable form of energy acceleration in the metagame. ogerpon's ability might only accelerate to itself, but it also is on a basic pokemon that helps you draw a card, so it's significantly more versatile. regidrago vstar decks, several of which got high-level results at NAIC, proved that with energy switch, ogerpon's self-acceleration limitation isn't nearly as much of a problem when the ability is on a basic pokemon. there's also no denying that charizard ex, gardevoir ex, sada's vitality, mirage gate, baxcalibur, and even xatu are all far better forms of energy accel.
hydrapple's attack is also bad. again, for a stage 2 pokemon that is already hard to set up, you need significant setup to make this attack actually do significant damage. darkrai vstar, who shared the same attack but on a stage 1 vstar, had more reliable acceleration to boost its attack (dark patch, galarian moltres v, and single-prize galarian moltres). and even then, it failed to ever be more than just a rogue deck, only getting 1 really notable result. that same attack, which has already been deemed to generally not be strong enough, is now on a stage 2 pokemon.
i hope i'm wrong! i would love for hydrapple ex to be a viable card, so i'm hoping someone can prove me wrong. but hydrapple ex seems really really bad.