>>46083810Kangaskhan: Weid situation involving the baby, probably easiest just to leave it single stage and not raise questions. Got a mega.
Pinsir: Became counterpart to Heracross, who does not have a pre-evo or evolution. Got a mega, and so did Heracross.
Tauros: Became counterpart to Miltank, who does not have a pre-evo or evolution.
Lapras: Didn't need an evolution. Probably got overlooked for pre-evo because it primarily exists as a rare encounter or gift Pokemon that you're encouraged to use for surfing. A smaller Lapras would seem less appropriate for riding on. Didn't get a Mega, but got a Gigantamax.
Ditto: No reason to grant an evolution. Having two kinds of Ditto could lead to breeding mechanic confusion. Pokemon's competitive viability was fixed by giving it Imposter ability.
Aerodactyl: Lategame fossil, grants you an immediately strong Pokemon rather than a fossil that will need to be evolved. No reason to grant it a pre-evo because of this unique position. Got a mega.