Malstrain mind controlling pure strains is pretty cool.

Malstrain corrupt regular nids.

Reading up on some Necromunda lore.
It seems to be canon that Malstrain DO in fact overwhelm and corrupt other tyranid organisms and fuck up their reproduction by causing more Malstrain.
Explains why the Hivemind wants nothing to do with the Malstrain on Necromunda and intentionally avoids it.
Source is Necromunda: Book of Desolation, page 47.

So when are we getting a malstrain hivefleet?