Don't waste money on fancy oil for this issue. It sounds beyond anything that oil could remedy. Redline MT90 is the best oil for Toyota transmissions based on general consensus so once everything is working you may consider going that route.
If you double clutch it when shifting does it help? Letting out the clutch between gears helps spin the synchros to match the gears. If this makes a significant difference there is a chance that someone put the wrong oil in the transmission causing the synchros to not work properly. In this case, find the cheapest GL-4 rated gear oil and swap it out.
