How many acres is your garden and how many of them will become the new pond? It sounds like you are planning a fishing pond, not a garden pond, if you are looking to stock pike. Garden ponds and fishing ponds have different needs. According to sport fish stocking resources, for a pond 1 acre in size and at least 8 feet deep, you should only stock 2-4 pike per surface acre. So just keep in mind that if you stock with northern pike or muskie, they eat any other fish in the pond, and they have to be fed other fish. For muskies (closely related to northern pike, but bigger), they recommend only 1-2 fish per surface acre, some guides say that you can have up to 4 northern pike per acre while others stick to no more than 2 per acre. Keep in mind that you can't stock just pike: they have to eat something, so you have to not only consider the two pike an acre can support, but also the stock of something they will eat (like bass) and since they eat constantly and aggressively, you will likely need to restock that food source repeatedly unless the food source fish is well established before adding any pike. Guides say pike eat bass, and to stock 50 bass per acre. Logically, that seems to imply that you can stock half pike and half bass, at half the rates, so if it's max 4 pike, and max 50 bass, you should be able to stock 2 pike and 25 bass in a single acre pond. You'll also need to stock something to feed the bass though. You will have to continually restock them if you choose minnows alone, but it can be done. Many resources say to
stock minnows to feed bluegill, stock bluegill to feed bass, stock bass to feed pike. What it boils down to is how many acres is your pond, and if your answer is less than 2, it's just not practical to stock it with pike because they require so many other fish be stocked to support them. They also reportedly do not do well in small bodies of water, preferring large lakes. Most sport fishing ponds require aeration, which can be read about at
https://americansportfish.com/services/pond-maintenance/aeration and
http://www.dunnsfishfarm.com/aeration.htm.
Resources:
https://www.bassresource.com/fish_biology/pike.html
https://www.aquaticbiologists.com/fish-stocking/
https://keystonehatcheries.com/blogs/gamefish/general-fish-stocking-recommendations
https://www.canr.msu.edu/news/tiger_muskies_to_stock_or_not_to_stock_okeefe16