It is not recommended that a new owner in Ontario move into the property to evict unless they actually intended to do so at time of purchase. However if these tenants are what you say they will likely be a very difficult tenant not worth the trouble of keeping.
I strongly advise they not make the mistake of trying to be friendly or lenient with them. They will manipulate you to their advantage.
Having said that an experienced landlord may be successful taking the approach of evicting for personal use in which case it is advisable to remain in the home for a minimum of 1 year. The reason being that a tenant may file an application with the board up to one year after moving out of a unit.
Depending on the actions of the tenant it may be safer to simply live with the tenant but at the same time being sure to follow all RTA regulations to the letter. In the case of a tenant that knows there "rights" being tough, issuing every notice immediately, especially N4s, 5s,6s etc is often the best method to drive out a troublesome tenant. You need to make sure there lives are as miserable as possible while at the same time maintaining your own sanity. If the tenant is knowledgeable on how to take advantage of and abuse the system expect a difficult battle especially when dealing with the LTB and tenant duty council. It could take a very long time depending on how belligerent the tenant is. There is no easy, quick method to evict in Ontario even with cause due to the intent of the board to protect tenants. Aside from non payment of rent issues most other landlord applications are rejected.
Unfortunately in Ontario getting rid of unwanted tenants is near impossible and will not be accomplished with the support of the LTB. The mandate of the LTB is to protect the rights of tenants to the detriment of the landlord and all other tenants.
Bull headed persistence along with a very high level of understanding of the RTA and philosophy of the LTB are your best weapons. Or as some less professional landlords often attempt you may offer a bribe to encourage the tenant to leave but this has the potential to backfire on the landlord. What it turns into is extortion on the part of the tenant.