This is sad. Ok for one, if you're only training one Pokemon then they should be strong enough to tackle the Pokemon League almost single handedly. In Ruby and Saphire I used Kecleon and Blaziken THATS IT and beat teh E4. That doesn't mean to go through it all witht hat one Pokemon though, I also had Groudon (Level 45) as support to deliver revives and healing items with just in case. In Pearl I used Gastrodon, Staraptor, Torterra, and a very weak Palkia along with 2 level 20's to aid in reviving and such. I made it through fine.Just bring Blastoise with your other strongest Pokemon and you should be fine. Venasaur is the only one I can think of off hand that you'll have trouble with in which case just teach Blastoise Ice Beam.If you still need help then get Blastoise to level 65 or so then try again and you should be fine. Just stock up on Revives, Lemonades, and Hyper/Max potions. Maybe give one of your weak Pokemon that one iteam that keeps them at 1HP on a fatal hit at full HP (If it exsists in this game, I think its called Focus Band)As for Blastoise himself I'd suggest giving him Surf and Ice Beam. As for other move slots I can't really think of anything, maybe Body Slam. DON'T teach him Skull Bash, it'll be a waste of time. Notice that both of those moves (all three in fact) have only 15PP which means you'll probably need some Ethers or Ether-acting berries.IF YOU STILL CAN'T DO THIS:GO out and catch Zapdos as (IIRC, he learns better attacks quicker than the other two) ALl you really need is Thundershock/Bolt and Drill Peck and you'll be fine. Zapdos is found at the Power Plant, use your MAster Ball if you're desperate, seeing as it'll be a tough fight with Blastoise. Now you have another "healer" (Like my Groudon) AND someone to take on Venasaur (Drill Peck obviously...)