1. Amount Size Limit?

Do not exceed 10 billion, otherwise it will cause errors
1.2.5+ supports up to terabyte

2. Which Holograms Are Supported?

HolographicDisplays or CMI(1.0.9+) or DecentHolograms(1.3.8+)
When multiple exist simultaneously, priority order is: DecentHolograms > HolographicDisplays > CMI

3. How to Generate Holograms?

/pt createHd [type] One-click creation of corresponding ranking list (type can be seen in commands or tab reminders)
/pt createHd [variable] One-click creation of corresponding variable ranking list (1.3.5+)

4. How to Use Any Player's PAPI Variables to Generate Ranking Lists?

Configure in papi.yml (there's an example inside that you can refer to) then reload the plugin

5. How to Move/Delete Existing Rankings?

1. Repeat the generation command, it will automatically replace
2. Modify coordinates in configuration and restart the server
For those generated using createHd command, set the enable node to false in hologram.yml to close       
Same for those configured in papi.yml, set the enable node to false to close 
Do not delete directly (direct deletion requires server restart to take effect) because HD deletes holograms based on old coordinates
3. You can use the command to move position /pt moveHd [type] (1.3.5+)