Please help me!

[Dragonfree]

Okay. How DO the weaknesses and resistances work for dual-types with one type weak and one type resistant in R/B/Y???

[BigBubb]

It's 1x damage. It's just the game's screwed up in that aspect when it tells you that Flamethrower is 'not very effective' against Lapras, even though it does 1x damage. Ice is weak, water is resistant. 2x1/2=1.

[Chris Watarimono]

If that's the case, the weakness and resistance will cancel each other out and the damage dealt will be neutral, much like when you use another attack that not super effective or resistant/immune to the target. For example:

Muk (Poison) v. Venomoth (Bug/Poison)

Muk used Sludge!

*Here, our friend Muk is using a poison attack on Venomoth. Normally Muk would go last, but he'll be first for this example's sake.*

It's super effective!

*Pay no mind to this incorrect statement. Either the translators or script writers either made a mistake by reading off only one of the types and ignoring the other. But normally, when an attack like this hits, the second type also takes a part. Since Sludge is a poison move, it's super effective on Bugs. However, since Venomoth is poison as well, and poison is resistant to itself, the damage cancels each other out and the type damage remains neutral.*

That's pretty much how it works. In PSI, the game automatically fixes this dual-type strength/weaknesses during the Stadium duels.

As for Gameboy battles, I'm not fully 100% correct, but more like...er...99.6% correct. :D

[Dragonfree]

Thanks. That "It's super effective!" really confused me.

[Amphatoast]

i think the reason it says "It's super effective!" and "Its not very effective.." is because of the 1st type of that pokemon like lapras 1st type is water so a fire move would say its not very effective even though lapras 2nd type is ice. If it was the other way around, a fire move would say its super effective even though it isn't since lapras 2nd type in this case would be water.

[Dragonfree]

I guess if it was... uh, Gyarados (Water/Flying) and you used an Ice move, it would first check type 1 (Water) and change the message that's going to appear into "It's not very effective..." and then check type 2 (Flying) and change the message again into "It's super effective!" That should fit, because it says Ice is super effective on Gyarados.