Since Explosion doesn't half Defence anymore,should it still be used by Pokemon like Steelix and Metagross?
I'm thinking of training a Steelix with Explosion but I'm not sure if it'll be as useful as in Gen IV.
Not in Gen V. In Gen IV it is great. Now.... its BP dropped. HUGE. I think its only got 150 now. Something like that. Its on Serebii.
I don't think it would be so useful, but it's still a good last resort. Although most pokemon that used it now can replace it with a more useful move, and in the case of Steelix, like Heavy Slam or even Aqua Tail (combined with Sheer Force).
It won't halve defense which is true in turn making it less powerful. however in some situations it could still be used good. im not sure y they changed it back but you know...nintendo...