Sorry to bother you. I'm glad you're enthusiastic about The Ones That Got Away, but it would be much appreciated if you put your videos in spoilers. It really clutters the page and can even slow down the load time for some people because it has to load 5 videos at once. Thank you!
I personally find him pretty easy with Marshtomp due to the part ground type meaning it can just take the electric attacks without taking any damage, with the most of it coming from the likes of Sonicboom against them.
Seeing as I've made next to no progress just sitting here playing in the Game Corner saving up for Flamethrower, I'd say I really need to get some training in for Wattson. I can't wait for Makuhita to evolve though, should add a significant boost in power to the team.
That's always my plan for Liza and Tate. Take a bulky water type like Swampert and hope for the best. Also, if possible, you could give a fast team member a dark or ghost move depending on whether they have higher attack or special attack and they could deal quite some damage to psychic types.
Yeah, Hariyama's a pretty specialist Pokemon, but when you face Sidney, if you still have him, don't start with him because of the Mightyena having Intimidate. If you take that out, then switch in, he'll probably one hit all of Sidney's team.
I never really used a Manectric until I tried out my cousin's old Emerald team of those four and found they work really well, as long as they all have diverse moves. In my normal playthroughs, I usually struggle with Water types because I rarely use a grass or electric, because I always have a Fire, Water, Flying, Fighting, and then usually a Psychic and a Ground.
I've always found a good group to be Swampert, Hariyama, Swellow and Manectric because they all cover each other's weaknesses very well.
If you struggle with speed with Hariyama, try using Fake Out and Vital Throw because Fake Out by a Pokemon with high Attack can be devastating and Vital Throw always goes last, while always hitting so it takes advantage of it's low speed.