You said Pikachu is very frail, and can't set up because of it.
Maybe a dual sceene such as Cresselia could be helpful to you.
It may allow you to set up easier, and it has leviate, which can be helpful to Pikachu,
and it can also learn Thunder-Wave.
I'm not quite sure who Cress would replace however.
I thought Dragonite at first but Roar must be very helpful to you, so you know who to eliminate.
Maybe Gallade?
I haven't put much thought into this, but I'd go with Surf on Pikachu so hopefully you can KO magnezone.
Hp Fire might be a good idea.
It'd hit Scizor hard, and Magnezone. And if your behin a sub, scizor would only be able to break it, as it'd be KO'd by Hp Fire.
Will-o-Wisp on Heatran might be helpful to.
I think a Swampert lead could be useful. Heatran covers it grass weakness.
And Swampert can Roar.
Skarmory seems like it'd be useful on your team. Maybe it should replace Dragonite?
I feel stupid posting this next part, but might as well say it. Maybe something positive will come out of it.
Now, bare with me on the next part. I'm tired, so I'll probably wake up tomorow and feel like an idiot.
I made a Pikachu team (Very quickly..So theres probably wholes in it) and I think you should give it some thought.
Here it is:
Swampert, Skarmory, Gyarados, Celebi, Heatran, and of course Pikachu.
It has a Grass/ Fire/ Water core. Skarmory acts as psuedo hazer, Gyarados would be Bulky Taunter, Celebi's leech seed
would be helpful to Pika as well. Heatran would be scarfed.
It has two pokes with Roar to rack up indirect damage, and to scout there team.
Celebi would also have Thunder Wave for support, so would Gyarados. And I'd give Heatran Will-o-wisp.
I know its a drastic change.. And it probably wont work with how it is now, but it has a grass fire water core which is very helpful.
I'd give it a try and see how it works.
Blue text = I forgot Pikachu's gonna need a lot status spread, so ignore the blue par t.
I figured I might as well leave it incase you see a good idea in it somewhere. Or it gives you a good idea.
I feel pretty brain dead right now, so thats all I got.
I really like your Pika team Idea. I loved him in Yellow :D (And I still do love him)
My review obviously wasn't the most helpful out of all these but I hoped I helped a little. Thanks for the review on my RMT c:
