lol i understand that but why not just use thunder and have rain dance which would boost the surf instead of weaken it as well as give thunder 100% accuracy?
it would only be for fighting other water pokemon. the only things water moves are weak against, is grass pokemon and other water pokemon. Lapras already can have an edge on Grass because it's an Ice hybrid and packs a strong ass ice beam, so if i give it an edge over water too i can literally have no trouble beating any pokemon type with Lapras.
so if i use Sunny Day, yes it weakens Lapras's water moves. but it also weakens the other water pokemon's moves. yet while that pokemon probably still has to use its shitty water move to attack me, i can just use solarbeam, so i'm weakening their move AND using a powerful move that is also super effective, without having to wait two turns for it to strike.
besides, i already taught my Magneton Rain Dance and Thunder.