There are several possibilities. Here are a few, and there are likely to be many more.
bate
fate
gait; gate
hate
late
mate
Nate (boy's name, or nickname)
sate
wait
Berate, hate, Kate, you're late, fate, date, gate, Nate, pate, rate, sate...
If you mean fate: hate, date, rate , grate, great, bait, mate, ate, eight, kate.
Actually, nothing perfectly rhymes with complicated...BaitedBatedCoagulatedCollaboratedCommemoratedCompensatedConcentratedConfederatedConfiscatedConsolidatedConstipatedContaminatedContemplatedCooperatedCoordinatedCorroboratedDecoratedDemonstratedDenominatedDepopulatedDeterioratedElaboratedExoneratedHatedViolatedOverrated
ate, Bait, Date, Fate, Gait, Gate, Hate, Kate, Late, Mate, Nate, Rate, Wait,
Gate, rate, mate, hate, date, late, fate, wait, Kate, ate, bait, quake, etc.
Ate, bait, crate, date, fate, hate, late, mate, pate, rate, slate, skate, wait, weight,
Bait Crate Date Fait Fate Freight Gate Hate Kate Late Mate Rate State Wait Weight
Eight It's not spelt the same, but it still rhymes
Date.
date
skate, date, late, rate, wait, mate, Kate, hate, Tate, gate, bait, trait, fate, plate, grate, crate
carseat