E.g. Soundgarden, Tad, Melvins and Alice In Chains

Alice in Chains was hair metal before it was grunge. There's a definite similarity.

Yeah.

AIC is my fav band from the grunge wave, they’re also the most musically talented of that wave. What got me into them was last year when my dad let me borrow the Jar Of Flies cd and it was amazing

Nice!

Some Nirvana songs are also more metal than grunge in my opinion. (E.g. Negative Creep (almost thrash metal), Endless Nameless (noise rock mixed with metal), Sifting (doom metal vibes), Scentless Appentice (kinda black n' roll), Pen Cap Chill (groove metal-ish, same for Floyd The Barber), Annorexorcist (also close to thrash metal), Come As You Are (kinda similar to darker power ballads) and Paper Cuts (also groove metal-like).

Don’t forget Breed

A cross between thrash and sludge.

Yep

School is more traditional heavy metal.