I might be repeating myself but I would do this.

All remaining darts to Hartlepool with some Manviro and ADL going to South Shields. This should in theory help to standardise the fleet at both depots.

30 E400 MMC. 25 for Newcastle 5 for Stockton. Some of the 58 59 plates could then go elsewhere or be used as spares. If any are not needed then they could move to Sunderland for the E and X24 X34.
5 at Stockton mainly for the 36. some of the Man 300 could then be sent to Hartlepool.

20 Enviro 200 MMC
10 For Hartlepool 10 For Newcastle.
This would see off the remaining Manviro at Hartlepool although some of the better ones could be sent to Stockton in a reserve fleet for both depots to use if and when needed. Any of the remaining none enviro MMC at Newcastle to be sent to South Shields.


Depots
Newcastle both depots. Enviro 400 Enviro 400 MMC, Enviro 200 MMC

South Shields Manviro 200 Some man 300 ADL Enviro 200

Sunderland Enviro 400, Enviro 300 (gas buses) Enviro 200.

Hartlepool Manviro 200 ( Reserve) Enviro 200 MMC. Dart SLF. Man 300

Stockton. Enviro 400 Enviro 400 MMC Man 300 Manviro 200 ( Reserve and spare ) Enviro 300 ( all types ) Enviro 200 MMC.